How is this any different than GOG's format?
Erm... you do not even need to reinstall GOG.
I mentioned Gog... and that was my response to why I'd prefer a key over a DRM-free Standalone installer (like the one from the dev site).
I'm done keeping files around, that includes CD's, DVD's, Boxes, and even Installers on my computer. I'm way too chaotic to keep track of that, nor do I have any inclination to spend HD space on something like that. I buy digital exactly because that allows me to not worry about local copies and I can always get them off the internet when I need them.
That being the case, there is very little difference to how I use GOG and Steam. The fact that the installers are standalone and DRM free are irrelevant to me, as I don't want them taking up space locally anyway. When I need them, I download them. If Gog were to go down, even *if* I had the installers, I'd still go looking for another service which offers digital downloads of those games. In that sense, Gog going down, or Steam going down, is really not all that different for me.
Doh.. slightly offtopic there.
As I said, I already mentioned GOG as an exception there, since it's a collective place for your games as well (assuming you mostly buy here). However, the comment wasn't necessarily about Gog, it was about any DRM-free installer, or in this case partly in response to the one you get from the developers website, next to the Steam copy.
And realistically speaking, I prefer Steam's client interface for downloading/installing over Gog's downloading/manual installing, however that may be because I never felt inclined to use the Gog downloader, which may be more than just a different way to download the installer by now.