Yes, I have this exact same experience. And even though there are some 'old gems' I still should try (Grim Fandango certainly being one of them), I also find that I've come to dislike certain games that I used to be quite fond of. For example all Sierra Online adventures, which seemed quite lengthy and rich in content at the time, now seem somewhat shallow and really short, even though I can appreciate the music or ambient sounds much more nowadays (or less, when I play a game with an awful soundtrack, such as Kings Quest V for that matter).
Currently, I only like games like HL2, L4D1 and 2, and some others. Civ 5 didn't manage to grab me yet, and all those fancy shooters don't seem interesting at all.
I think there are two reasons for this. One is that I used to marvel at the worlds in which I would be able to escape, but as I've grown older I've seen movies and read books which were much better in 'sucking me in', to the point that games' experiences just are too shallow to me. Even though games have one clear advantage over books, and that is the way in which a player can shape her/his own story.
The second reason is that several years ago, games seemed to become more and more advanced and pretty. Right now, the difference between a new game and one that has been out for, say, some years, just isn't big enough to get me all enthusiastic (admitted, I don't have the means to run such a game anyway). I used to marvel at all games reviews in the magazines; now, when I go to, say, GameSpot, chances are pretty much 50% that I'm bored to tears at what I see, no matter what graphics these games feature...