On a more serious note, I think we've entered an era in which WotC is less interested in D&D as an RPG, and more as a brand. This has been talked about extensively, but there's a possible/probable result that I don't think is talked about much. Because of this, they want some degree of stability with the game itself - they want to sell "Dungeons & Dragons" in a wide variety of ways, and don't care as much about the actual table top game itself - as a game. So as long as people like the game, they won't change it much.
Meaning, they're no longer run by people who are interested in the evolution of the game itself, imo. They're not thinking, "How do we make D&D better?" but rather, "How do we find more ways to profit off the D&D brand?"
I'm not talking about specific game designers or even the D&D sub-group as a whole, but the decision making folks at WotC and Hasbro - and thus the "bottom line."
To me this is kind of sad. I was never an "edition purist" but always looked forward to new ways the game could be played, whether that was a new edition or an experimental supplement that turned the game a bit on its head (think later 3.5). Meaning, I liked the fact that D&D was, in the end, run by gamers - people that loved the game and wanted to explore it in different ways. But over time, "corporate creep" has gradually taken over - especially over the last five years or so.