I prefer GOG for most games, using steam when necessary. However, while the GOG version of Skyrim is the best vanilla experience, it's current restriction to 1.6.659.0.8 (or whatever specific 1.6 version) makes it very difficult to mod.
Workarounds can be done for most issues with the GOG version, but since so many mods/modpacks are built off the 1.5.97 version, it makes it, to my knowledge, impossible to use comprehensive modpacks (Wildlander, etc.) and older, unmaintained, but functional mods.
As such, are there any plans to make 1.5.97 available on GOG?
Since the GOG version is so new, and the steam version so ubiquitous, there is no guarantee that modders will patch 1.6.659, rendering the GOG version obsolete in comparison to the steam version (by my reckoning.)

I might be missing something here, but why is the GOGversion obsolete? Why can't you play the game without mods?

Sure, if you're happy playing without certain mods, it's fine as is.

But lots of people love to play Skyrim with mods, sometimes lots of mods. These mods can make the game even better for those people. He's hoping that an older version can also be released here so that those mods can be applied, which seems reasonable enough to me, as long as both versions are made available.

To my knowledge (fledgling as I only gotten into *Skyrim modding today) It's a complicated answer.
Skryim has been on Steam far longer, so most mods assume you have the steam version. This wouldn't be an issue, but GOGs pathing and in built KSVE are different than steams pathing and (to my knowledge) the official KSVE variants. Add to GOG being restricted to version 1.6.659.0.8, and a VERY large chunk of mods need patching (or, I would assume, redesigns) to work with the GOG version.
Theres also some other thigns, specifically something to do with NGs, which I'm largely unfimilair with. And, I think, the lack of a DRM in the GOG version means certain modpack's piracy protection (like Wildlander [the reason why I got into all this]) would need to be updated.

There's probably a buncha other reasons why it's difficult to make mods work with GOG, but from what I know already it'd be a monumental workload for.. anybody. Having a GOG 1.5 version would help a lot, but I'm too unfimiliar with coding and Skyrim modding to be sure that there ain't any other factors to the situation.

Sounds almost like trolling... whats going on here?

Nope. the current GoG version is NOT out of date, it is up to date the best way possible. While 1.6.659 is a great version, the newest version is 1.6.1079, which is identical to the newest "Steam version", although another EXE with another version number.

There was a version in between, 1.6.1030, which was not used on the Installer and i am glad it had been avoided because this version was just "a broken 1.6.1070", so, nothing we would want to put into a long time archive.

I currently play a extremely modded Skyrim, as a GoG version... running fine so far.

A screen of the mod "Akis Tower" and some weather mods. The Character got some KS Hairdos Hairs and a CBBE Body with some remastered Vanilla armors. The flowers are from 3D Cathedral HD. Ah yeah, she can "dual sheath" using the "simple dual sheath mod". Freshly modded...

O, pardon. I probably mixed up the version, though that's not important.
The point is not that I need the latest version, but a older version which was recommended due to it being more compatible with a good deal of mods. Specifically, 1.5.97.
If you've ever modded minecraft, it's a similiar-ish deal. While there are many mods that are fine with the latest release version, there are versions that are much more compatible with a greater deal of mods. So, modpack authors favor those mods, to my knowledge. Like I said in the first post, this is my first time modding Skyrim, so I'm unfamiliar with a lot of it. My main hiccup is Wildlander being incompatible with the GOG versions for the reasons listed in my previous posts.
I can share my references if necessary.
(The Steam version of Skyrim has the option of 1.5.97, while the GOG version does not.)

No, GOG is never going to have the 1.5.97 version of Skyrim, nor any version of Skyrim that is anywhere on par with the Steam version in terms of mod compatibility, and most the good mods & mod collections are not compatible with the subpar inferior GOG version of Skyrim.

For the GOG version to be brought up to par with the Steam version, then the Bethesda devs would have to make the GOG version of the game become identical to the Steam version (as it should be), and probably also GOG would have to be adamant about insisting that they do so, and probably also GOG customers would have to be adamant about demanding an equal version.

But unfortunately, that ship has sailed, and neither GOG, nor Bethesda, nor the majority of GOG customers care about the fact that the GOG version is the sucky, subpar version with very limited mod compatibility of the best mods and also with the best mod collections; and so, since almost no one cares about these very important issues, that is why the GOG version will forever remain an inferior, trashy version (I care though, and I am still upset that I got ripped off by being fooled into buying the GOG version of Skyrim when it first came out on GOG, without knowing at that time that I was buying a sucky version with limited mod compatibility, because this fact was in no way disclosed by GOG, and on the contrary, GOG marketed the game with phrases in the trailer like, experience a decade's worth of content, making sound as if all mods would work with the GOG version, even though most of the best ones don't).

Most mods will work just fine with newer versions of the game. Those mods who actually need an update simply should get an update... and so far i only found one being an hinderance to me, which is racemenu and even on "that other version" it is currently causing issues.

The 1.0.659 version works fine with as good as any mods from Skyrim SSE.

The newer versions got creations club content build into the game at "no additional cost"... so in theory the newer versions are supreme... they simply need proper support for some version sensitive mods, thats all. I really got ZERO clue what you mean...

Who are those "supreme mods" you can not use on GoG anyway? Do you know their names?

Ya, that's exactly what I feared. It's not much of an inconvenience, I just prefer GOG, and would rather not wait God knows how long it takes Steam to put Skyrim on sale again.
Hopefully it gets worked out in the future, but I doubt it's gonna be soon.

Thanks m8, peace.

Can you please tell me your issues, i mean very precise... thank you.

WHAT is not working for you?

The reason why i got into this was a modpack called Wildlander. Idk if it's anything special, but it's comprehensive enough and I wanted to spice up the game.
FAQ page says that it's incompatible with steam, went to discord and read previous post by a dev explaining (somewhat) why it was incompatible. Looked up a buncha stuff, now here I am.

O, here, sec.

If the mods require the script extender (IIRC, it's been a while so I may be forgetting the technical descriptions, but the point stands regardless of the technical words), then no, they will not work with the GOG version, and the only way that changes would be if the mod makers make a GOG specific version.

RaceMenu that you mentioned is a perfect example. Originally it did not work with the GOG version. That mod maker eventually made a version that did. But most mod makers like him are not going to do that, and so their mods will never work with the GOG version (or if the real solution happened, which would be for Bethesda to give GOG an identical version to the Steam version).

As for what are those "supreme mods"...how about the most popular & most endorsed mod collection for Skyrim on Nexus Mods, which is the site that GOG partnered with to push the supposed great mod compatibility (but not really) of the GOG version. It has not been compatible with the GOG version (I didn't check lately if it has ever been made to be so).

When I asked the curator a long time ago if he ever would make it compatible with the GOG version in a way that is 100% equal to the Steam version, he told me that no, that would never happen: at most, GOG would only ever get scaled down, worse version of the collection, with the Steam version always being way better.

So, they demand a "downgrade" from you in order to get their mods-package to run? Hilarious... i would not even bother supporting it. They should simply upgrade their mods... not downgrade a game. The GoG version got the smallest issues at all because it got a installer that can, in theory, last forever... unlike the Steam stuff, always at risk of losing it at some point and always have to "force your downgrade somehow", this is hilarious.

Yes, i still got both GoG installers, although GoG is only offering the newest installer, which sucks.

Let me condense this to the best of my ability:
The GOG version is locked to the latest patch version, which makes it incompatible with the modpack I want to use, as well as many other modpacks (I would assume). Additionally, the lack of DRM on the GOG version may cause issues with any modpacks with in-built piracy protection (because, why not have it?) and the in GOG version has a custom variant of SKSE which can cause issues, though I'm unsure on the specifics. There's also something to do with a program (or something) called NG, which has something to do with how DLL. files are read.
That's the jist of it, though I could be forgetting something, and a lot is probably lost on me.