OldOldGamer: In may case, I stopped shopping at GOG, waiting for them to make some sense of their business.
If that will ever happen.
So did you stop buying digital PC games full stop, or does some other store handle it better?
Quickly what I checked on Steam, in the search list view the already-owned games are not differentiated, but they have a small "in account"-icon in them, somewhat like the current GOG design. They don't differentiate the already-owned games in any other way.
I agree though that the old way of greying out the owned games and separating them in the bundle view was better than the current way. Then again I thought the OP was complaining how they are shown on the main page, but not sure. He seemed to indicate it has never worked well on GOG, so I presume he was not happy with the old way either.
Anyway, the most important to me is that the already owned games are marked somehow so I don't have to trying to remember them by heart or check them elsewhere.
Leroux: GOG doesn't really listen to the users' wishes and complaints.
I've had a completely opposite experience. For instance the "Galaxy embedded to game installers", which they first "fixed" by offering two sets of installers (one without the Galaxy installers, which was enough for me), and later completely getting rid of the embedded Galaxy installers, like people suggested in the beginning. I also complained about that but I did feel they listened to people's complaints, instead of e.g. saying "sorry but this is how it is from now on, deal with it".
Sure they haven't responded to and complied to each and every complaint or wish someone might have had, but then many of them aren't necessarily worth the effort. Like, the original suggestion in this thread. If they started fulfilling each and every user wish (regarding the web page and store design), many of which are contradicting, then this place would really be a mess.
To me, the first litmus test to all these complaints and wishes is, how have other digital stores (like Steam) handled them. If they don't have a similar feature, then maybe, just maybe, there is some real reason NOT to implement such a feature.