That's because they are not that good not that you are getting old. Cartoonization of Diablo (there is fucking rainbows in diablo 3!!!), Consolization and dated graphics of Skyrim etc. sux
I am 'old' late 30s and been playing SC2 a year straight. It's only half as good as BW, the most perfect game of all time, - but still much better than most modern reincarnations of franchises.
No one wants to admit they ruin these franchises and in many cases are living off past success. Sales are created by a feedback loop. Like a movie everyone goes to see and you walk out thinking "that sucked." many games are the same way.
Diablo 3:
I never bought into people whining about Diablo 3 graphic. I'm thoroughly impressed with the Beta. They polished everything up (clean interface, WoW-like cool down indicators, great UI showing real-world DPS- no more confusion about which weapon is better, etc).
As far as artistic direction, they listened to the whining a lot. Lot of the colors are muted and desaturated. I think it's fine. There's plenty of gore and darkness. It feels like an action packed beat'em up (complete with great screen shakes every time you pounce) than the classic gothic ambiance of Diablo 1.
The game itself is great. It just feels same old to me. I mean even the plot is completely rehashed, not just paying homage. Visiting Tristram for the third time again? Killing Griswold for third time again? Killing Leoric third time again? wtf.
SC2:
I also think they did a great job here. It's boring to watch SC1 pro matches because Terran is all about parking Siege Tanks everywhere and spamming Vulture mines. SC2 matches are more entertaining for me. BUT they did totally bastardize the story for the 13 yo mass market. The story is a total shit and I agree with the community. When did Raynor have a love interest for Kerrigan? He swore that he'd be the one to kill her for her sins (after murdering his protoss buddy Fenix). In SC2, suddenly all he thinks about is saving Kerrigan? WTF. Also Mengsk was a cunning, masterful leader. They turned him into a bumbling fat idiot who freaks out at press conferences.
Skyrim has dated graphics? I thought the stunning sandbox world was just jaw dropping. I have never felt so immersed graphically (not so much gameplay-wise) in a game. Yes there are better 'graphics' like Crysis 3, BF3, etc. But they don't have a consistent open world of few hundred square miles. You can't expect to have both.
As for what you said about living off of past success in today's world of triple-A titles and mega corporations, I totally agree with you.