I think your line was crossed a long time ago, you are just now ready to admit that. If you no longer agree with a company then by all means it's time to walk away... I would too.

We do know size might be an issue so GoG is working on it.https://www.gog.com/forum/general/offline_installers_with_an_option_to_install_gog_galaxy/post43

It seems likely it just won't be a 2mb stub installer. There is going to be some bloat and still - even being reduced to 50mb would be too much.

For the record I don't use Galaxy but I think it's good for GoG. I just think the way they're going about this is utterly wrong.

The line is crossed now. Galaxy was only some kind of unhappy event, but it stayed "optional" for a longer period. We can argue about "optional", but harsh lines are needed in my point of view. There is nothing illogical to have principles and GOG is giving nothing about that. So why should I care about GOG any longer? And it is also no matter how many games I have purchased or movies - also some started project never done it further and therefore a nice lie. What about Galaxy as Linux-client? Ah, of course: They are working on it, for also a very long period now. But yes: We can do more talking nice about GOG, which once was really good as GOOG OLD GAMES, but now? Nothing more than a cheap copy.

The problem's in the execution: instead of using Galaxy being the option, now the option will be not using Galaxy. A subtle distinction, to be sure, but what are the effects? Just a couple things off the top of my head:

1) If you happen to make an error during installation of your game, you'll end up installing Galaxy - something you don't want (this presupposes the user that actually has no interest in it). So, then you have to uninstall it - yeah, again, no big deal. But a pain in the ass. And this has the potential of happening repeatedly. The other way around, if you mess up, you just end up not installing Galaxy and just grab the software and install it. And you never have to worry about it again.

2) It adds bloat to the off-line installers. Again, not a big deal, as Fables seemed to indicate they were working on making the installers smaller anyway. But... it still makes the installers larger than they would be without it included. An issue for some people with limited bandwidth and/or storage space.

3) These are offline installers. Why would people that want off-line installers want Galaxy in the first place?

4) GOG is presenting this as convenience because the average user isn't 'tech-savvy' enough to install Galaxy themselves and apparently not 'tech-savvy' enough to choose to opt-in. (This is actually GOG's explanation). This is so incredibly ridiculous that one has to wonder why they're really doing it.

Sure... all valid points, don't disagree with you, but some people really push the boundaries around here of what optional means and what DRM free means. Call it what it is... a horrible decision.
Yes I'm aware, but at this point and time we are still guessing about this... while it looks like they at-least planned that, we can't currently say for sure if that is what will happen.

Apparently, neither can GOG:
https://www.gog.com/forum/general/offline_installers_with_an_option_to_install_gog_galaxy/post452/?staff=yes

Now That's What I Call Planning!, Vol. 92.

Actually, yes it does.

Case in point: there is a chat service which has just gained a team who are looking to code their own servers. These servers will be more secure than the official ones (which no longer get updated) because there are some exploits that they can add server-side protection against, so even the official clients will gain that protection (when connecting to the new servers).

You know what would help them achieve this? Protocol documentation, which is what I am suggesting GOG release. The fact that GOG can update the protocol if some flaw is discovered makes it even better.