Apart from Command & Conquer and System Shock 2, these games aren't really that old!
I think that the "problem" these days is that there are way too many games to choose from. It's the same when you're planning to watch a movie on Netflix or something; sometimes you spend more time trying to decide which movie to watch than actually watching it. And when you've finished watching the film, there are thousands of others that you can choose from, so unless the film is somehow exceptionally good, you'll just forget it and move on to the next one. Back in the day renting a film wasn't so easy, and because you actually had to go through some trouble to watch one, you would pay more attention to it and perhaps even watch it more than once before returning it. That little extra inconvenience is why music sounds "better" on vinyl, and that applies to other things as well, including games. Digitalisation has made games cheaper and much easier to acquire, but I think it has also changed the way we play games (and the way how games are designed).
Anyway, I'm good at ignoring questions.I just find it more difficult to get "attached" to games, music or films nowadays. I can't even remember the last time I played any game for a second time after finishing it. I have hundreds of unplayed games in my library, so I prefer shorter games, ones that don't take too long to finish so that I can move on to the next game.
Maybe I'm just getting old too.