EnigmaGrey: I mean, why would you expect it to change?
GoG's not Steam in terms of convenience. It requires manual validation and repackaging of updates (as far as I'm aware), in addition to coordinating the upload of any update with GoG's team. It can be a long, frustrating experience that takes time away from other tasks, so it's only done when it has to be done once.
We're looking at automating the upload itself of each OS in the future, but that system is not in place yet, so it's of no help.
Edit: Sorry, I realize I'm being bitchy here. I know it's unfair that Steam gets the build first. It's just that we've had some pretty turbulent releases over the years that would have necessitated quite a few patches. With myself and Sasha handling QA, in addition to our volunteer testers, perhaps we won't be so gunshy in the future, but for this release, we're erring on the side of caution.
OK, GOG sucks in this regard, almost every game on GOG that is receiving any updates (be it in development or patches) lags far behind Steam version. And no one seems to be willing to use the GOG beta branch channels. So I believe you when you say that uploading stuff on GOG is long and frustrating experience. But that doesn't change the fact that you very well know that compared to Steam the GOG version is vastly inferior (major releases delayed by weeks, IWBUMS not available at all) and anyone who expects feature parity between Steam and GOG will be sorely disappointed. And there is absolutely no way to find this information when buying PZ on GOG. Even on Indiestone forums when you know exactly what you are looking for it is pretty hard to find. So please, put some simple warning about IWBUMS not being available for GOG into the store description.
Oh, and please look at the FAQ topic and change the "how often do you release updates" section, because the entire part about updates is for Steam users only and is absolutely misleading when it comes to GOG version of the game, to the point of it being deliberate lie.