I'm 40 now and also had a big passion for games, programming games. I still follow gaming news and I think it's totally fine to enjoy videogames throuhg Twitch, as games are entertainment after all ;)
There is probably an element of growing older. Same way I lost interest in reading sci-fi, I'm just not that much into virtual worlds lately. Playing a MMO has lots its appeal. I do enjoy Hearthstone a lot atm, and it's a game that demands a lot of presence and attention, if you're tired and misplay the game is very frustrating so it's definitely not a game to sit back and relax in my experience.
But there's something about the complexity of games these days. While Hearthstone is easy to approach, and people often cite the RNG aspect, it atually has far more depth than it looks. You can "net deck" a set of cards, and still perform really bad, and as you keep playing the same deck, find more and more depth to the gameplay and synergies you didn't even know where there, besides the obvious ones.
Then you compare that to your typical MMO: for example I've often wanted to come back to LOTRO. I love the music, the game has a lot of charm, and even for the main questline alone I thought the writing was quite good. But.. the game's UI is so bad, and the systems are so complex... that I boot the game and give up within a minute. I just don't have the patience to sit through hours of relearning all the systems for optmizing my character's build. It's very archaic in many ways.
Then you have games that are built around grinding and amassing virtual wealth. Personally I really don't like the way games are designed around auction houses these days, and the involvement of real currency. It really poisons the heart of the game. I boot Guild Wars 2 and it feels like I have to play "auction house wars". I have all these items in the bags that I'm supposed to put on there. And the game is supposedly free after you buy the box, but you are clearly being tempted with all sorts of thematic updates, and it's just plainly obvious how the game is designed around this. The irony is that Guild Wars 2 ends up being all about grinding, since it's like a candy box that requires virtual money to buy candies. You don't need it yes, but then you feel like you're playing a sub par experience. It's like saying, hey you can go to Disney Land on a budget, you don't have to buy any of the foods or trinkets there.
Then there is a social aspect as well. Although I'm bored of MMOs, as I don't have any close friends/family who plays games, I find it a little lonely to play a purely offline game. In Hearthstone, I am playing with other people, so there is a sense of connection, and that adds some depth to your experience. But then I have a game like King's Bounty Crossworlds which I really like, and I really want to get back to, but often I find I fire it off for 5 minutes and get bored just because it's me and the computer and all I have is the motivation to "win" the game. WHich in itself is very little incentive for me, as I see more and more games as an experience.
I'm looking forward to VR since those will be much more about experience, and I think we may see some innovation in how the games are designed. Maybe no longer so "win" driven, but more about experiences and relaxation as well as connection.
Just rambling ;)