Comic writers, even the best ones, have a "sell by" date. Or more accurately, a wall they just hit where the content they produce is no longer good. Like, for me, Chris Claremont is the greatest X-Men writer of all time, but by the time the early 90's rolled around he was done. Totally out of gas. And he was never able to hit those heights again. And eventually you end up with an abortion like X-Treme X-Men when they keep trying to recapture that magic and failing time and again.
Bendis is certainly well past his sell by date. Whether you think he was ever good or not, his early 00's run was one of the more historically formative ones in the industry. But the Bendis that was responsible for that run of Powers, Ultimate Spider-Man, Alias/Jessica Jones, that five year run on Daredevil with Alex Maleev among many other things....that Bendis hasn't existed in a long, long time. We're almost 20 years on from that Bendis and he just feels like a guy with not much left to say. Timeline wise, he's about to the "Claremont on X-treme X-Men" part of his career. His jump to DC was pretty much the standard "once untouchable big name company lifer jumps ship to the other guys for one last stab at the limelight." We've seen that one happen too many times to count. Hell, even Jack Kirby did it and he was the unqualified Greatest of All Time. Of course, his output at DC, while very misunderstood at the time, has been pretty well vindicated by history, so maybe he's not the best example.