I don't think games have gone to shit (a lot of old games were just rubbish when the nostalgia-goggles come off or cruelly unfair and not in a fun way or just as derivative as modern games, but of earlier things) but if you've been playing games for years, as most in this thread have, then you will have played a precursor to many games before. Some of the games in the last few years are ones that I think look absolutely amazing, but I just can't face playing them because I know it'll be just like playing an updated version of something I might not even have liked the first time round.
I've played Sim City and Sim City 2000 to death, for example - I don't /want/ another game that's like that but shinier with a couple of new mechanics. On the other hand, while I've played almost all the Command & Conquer games and got bored of the repetitive mechanics and playstyle, I really enjoy World In Conflict because it gets away from the same shit you do in every C&C game - it's just another RTS, but one that's different /enough/. But I /can/ see that some recent games are damn near perfecting these mechanics and people who haven't been playing games since they were a teenager can properly appreciate them.
A game that /is/ different can capture my attention still, but other ones? I've done it before. In theory I like FPS games, but they all start to blend into one so I tend to put on invulnerability and ammo cheats then wander round just having fun and admiring the graphics and level design without having to actually worry about doing things properly. Some of them still stand out (Far Cry 2, as an example, which I am making an effort to play properly) but most of the others don't do anything for me because I've played so damn many.
It's like your dad or grandad - they were with it, back in the day, and bought all sorts of pop music, but if they were still buying pop music you might think they were a bit odd because it's music for teenagers. Now I'm over thirty, /are/ all games being aimed at me? Probably not, because I'd suspect (with nothing to actually back this up, I admit) that late teenage and early to mid twentysomethings are the core gaming market, so of course the games will be aimed at them, and I'll be nostalgic for the games I played when I was that age and square in the sights of the manufacturers. Now, I play Prototype and much as I love it, I think "hmm, this is pretty violent actually, but still really good fun" rather than going "wooooah so much blood, this fucking rules! Holy shit I cut that guy in TWO"
I absolutely loved Dungeon Master. I played through it so many times. I honestly think no fantasy game I've played since has had that much atmosphere. On the other hand, I also had a disk box full of fifty other Atari ST games that were mostly crap, and the few others that I did enjoy, I certainly didn't play as long as I played Dungeon Master. But looking back, I couldn't tell you the names of most of those fifty games, because it's the good ones that have stuck.
Slight derail, but relevant - it's kinda strange... If you're around thirty (or started gaming early), you'll probably have played the start of most of the genres. I remember the release of Doom, Populous, Sim City, Dune 2 and Dungeon Master and others as well as playing at a time when Carrier Command, Pole Position, Outrun and Elite were still popular - I mean, these are the games that pretty much set down the genres and became the foundation stones for vast slews of games since. It's strange looking at Spore or The Sims and remembering that I once thought Populous and Little Computer People were amazingly advanced.