timppu: ... And also in this case, I have no idea why those installers that Galaxy would download too, would have to have the optional Galaxy client installation query/stub/whatever. Again, what does it have to do with anything? What would be its purpose and benefit?
paladin181: It's semantics at that point. The point is that both "offline" and Galaxy installs of the games would use the same installer, and because GOG wants to get Galaxy in faces and on PCs, they could satisfy that by having the option to install Galaxy in the installers. That way people pirating or otherwise unaware can still be informed about Galaxy and be given the option to try it and no one who doesn't want it has to be troubled with it.
Ok, but then we get back to the point that adding the stub or query to install the client has nothing to do with guaranteeing version parity. The reason to add it to all offline installers would be something completely unrelated (like GOG wanting to promote the Galaxy client to all those who don't use it).
Because that is what the OP originally suggested, that the "option to install Galaxy" in the offline installers would somehow guarantee version parity, or at least would be somehow needed for it to work. Not true at all.
With that suggestion, we would be back to the original mess where GOG indeed did already add the option to install the Galaxy client, in each and every offline installer. GOG backed off from that thankfully, and now the OP is suggesting GOG should try it all over again, with little changes.
Nah, I think the current way is much better, where the offline installers don't have such "query" (which would again just irritate people who DON'T want to use the Galaxy client, like in their previous attempt), and on top of that there is the web link to download and install the Galaxy client, which then automatically downloads and installs the game for the user. This latter option is for new users who want to use the client after they've purchased their first game from the service.
If GOG wants to improve the version parity between the offline installers and the "Galaxy versions", then that has nothing to do with that Galaxy client query/stub, but it would have to be solved some other way, e.g. what I suggested.