I'm just 24 and I'm starting to feel the same way. Every new game I play I just feel disappointed with a few days in and think about why I'm not outside doing something that will actually help me accomplish goals I have for myself. It just feels like, no matter how far the technology as come, none of the games out can give me the pleasure I had playing things like Pokemon Gen 1 and 2, or shooters like Timesplitters, Halo 1-3, Goldeneye, or had the exploration feeling I felt wandering around Oblivion for the first time. I think Dark Souls and BFBC2 have been the first games I've felt like were something new and captivating in a long time and those games are already dated. Skyrim was fucking great but I still didn't get as heavy of a sense of awe and wonder as I did when I played Oblivion for the first time.
Of course this has to do with nostalgia playing tricks on the brain to some extent; nothing new will ever be as good as fond memories. And some of it has to do with how the layout of gaming/growing up has changed things- even if you're playing with friends, you're still playing alone physically most of the time, especially with the near eradication of split-screen. All those "old" games I mentioned before were played surrounded by friends, either switching off the controller or playing split-screen or bringing my console to another friends house to LAN or just to play next to each other. Of course some of that is on us for growing up and getting busy, but no one really caters to playing like that anymore. It's all assumed to be done online nowadays, and I feel like that detracts from the experience.
However, the biggest reason I think I feel this way is that we aren't where we "should" be at in gaming. Yeah, games are getting larger, are getting better graphically, but all in all they're the same as the games being released years ago. There's not much innovation happening nowadays; not many major publishers are pushing the envelope and risking something that might not work but may make a new genre if it does. It's all just "safe" rehashes of old games. The same game but "bigger and better looking!" We should be able to do some absolutely crazy things with the hardware on both consoles and PCs now, yet we rarely see the crazy or feel captivating novel experiences anymore. I think the main hope is in crowd-funded indie games, but even that is turning out to be a scam a lot of the time. Even if I am nearing the end of my gaming career, I did have some great times and I'm thankful for that.