Hurricane0440: I do think that the option to donate money specifically to GOG does have some merit. I believe a large number of people buy games only on sale, so increasing the base price of games may have very little impact on the revenue GOG earns from each sale. In that case, providing another avenue for people to support GOG could increase their profitability.
This could also be an indication of GOG's finances, but I really hope that it's not the case. If it is, I agree that GOG might be better served by sticking to their core business of providing DRM-free installers and working with the community to provide launchers.
On my part, I may donate from time to time if I ever feel like it, but I'll be sticking to buying as many games as I can at full price as a way of supporting GOG. Donations have a place in community-driven projects, not businesses, in my opinion.
I honestly think sale culture is a double edged sword. It has undoubtedly devalued games and reinforced the idea they are merely disposable toys. It also provides longer term revenue tails for aging products, while lowering access barriers. The truth is that every commercial video game has a lifetime average sale price. If we could know what that is, you could charge just that without ever putting it on sale.
I personally think publishers would be surprised at how minimally their revenue would change if they just had lower fixed prices. I would be more inclined to just buy a game right away at 40 or 50 dollars, if I knew it was essentially never going on sale.
Given GOG is competing with Steam and libraries of games people often already have, they have limited options to compete. Price is the easiest one to control. It makes sense that to supplement that, they would essentially ask for donations or tips. I am sure charging a premium for the DRM-Free nature of the game was floated, but had poor projections.