Now I am confused...isn't a "good game" always a "good game"? No matter its age?

You could switch to list view.

Indeed, but we all have our certain... predilections and tendencies. In this case, our dear Garcia has an affinity for titles of a certain age. Perhaps he likes the way they look, handle, or enjoys owning some antique trinket that reminds him of his home or upbringing. Who knows! Either way, this is what is desired.

GOG differentiates between the release date and the date they were added to the store. Do you make use of the Release Date slider to adjust it to your preferences? Even so, when you mouse-over a game in grid mode, it normally displays a screenshot of the game instead. This is done in barely more than a passing glance. Are both of these features insufficient?

Included year with title might be okay.

But what GOG should be doing, is always displaying the original date of a game (release or creation) in its own field, and if needed a later release date in another field, as might be the case for a remaster or special release. And I guess you could have a date of when made available at GOG too, which should be another separate field again.

I definitely agree with this. There have been a lot of games where I'd be curious of the release date and I knew the release date listed on the GOG page couldn't possibly have been the original date the game released on. Things like "remasters" or re-releases often don't have the original date.