Majoru Oakheart
Adventurer
It's not JUST that. More people like real time games than turn based ones. Even the new Numenera game coming out which is the spiritual sequel to Planescape: Torment had a poll to ask all their kickstarter backers if they wanted the game to be turn based or real time and real time won by quite a bit. Though, they are going to make it pseudo turn based by having predefined pause triggers like Baldur's Gate.TB games are dead only in the eyes of Publishers who're drowning in creative bankruptcy and praying that if they keep releasing FPS's they'll be able to stay afloat one more year. Everyone else releases them and does just fine.
Turn based games are just kind of a niche market these days. If you want to make lots of money, you make your game real time. X-Com succeeded, I think, mostly due to nostalgia than because there are a huge number of people who want turn based games.
I used to play X-Com like crazy along with all the old turn based RPGs...these days I think about sitting down to play a game that's turn based and I dread it. It seems SOOO slow that I don't really want to play it. I even bought X-Com and haven't been able to convince myself that I want to dedicate that much time to making tactical decisions so I've never opened it.
Which brings me to the one "4th edition" game that did come out: Neverwinter. It isn't turn based and the powers that exist in the game are more inspired by powers in 4e than taken from the book. However, it does follow the basic structure of At-Will, Encounter, Daily powers and the class names and basic concepts are taken from 4e D&D. Ostensibly, it is a 4e game.A lot of people were not all that thrilled that 4E changed so much of the established settings (Baldurs Gate/Neverwinter).
D&D: Daggerdale was also a real time 4e game for XBox 360 that once again was more "inspired by" than actually using the 4e rules.