I wish Mike Mearls well and hope he has great success.
In all honesty, my gaming circle has never really given 4th Ed a fair shot. I think we played a total of 2, (maybe 3 sessions?) -- in two separate campaigns -- of 4th Ed.
Four of the seven people in my circle own the D&D core rules for 4th Ed. Nobody among us have purchased more than that, exception (me) as I bought an extra copy of the PHB.
The interest just wasn't there and there was a lot of resistance in my group. My gaming circle had made a tremendous investment in 3.xx books. I'm guessing between all the members of the 7 people in my gaming circle, we probably own, collectively, between 380 and 400 3.xx hardcovers? Something very close to that -- and the book count might even be higher than that, too.
Explaining the core reason for my group's resistance to 4E does not get much more complicated than that. The release of 4th Ed was just too soon for my group. I expect in another year or at most, two years, that will change. At that point, we'll give 4E a serious kick at the can. Right now, the group has "let go" of 3.xx and has move on to Pathfinder as of a few months ago.
I say "let go" because we aren't using any of those 3rd edition books in our Pathfinder campaign. We've started with the PF Core Rules and approached the game with a clean slate.
So that's just anecdotally my group's situation. Whatever it is that we did or didn't do in relation to 4E didn't have any real connection with the design of the game in terms of like or dislike. My group's reaction was rooted in the investment we had already made and was a reaction instead to the timing of 4Es release. My group's emotional reaction to the cancellation of the print editions of Dragon and, most especially, Dungeon Magazine certainly didn't help though.
When we get around to actually playing 4E and give it a fair shake, we might have something fair to say about the design of the game. Right now - we can't.
FWIW, my group has been recently playing Star Wars: Saga Edition and has been enjoying it a lot. Yes, even the skill challenge system has gone over reasonably well amongst the players of a group comprised of 30+ year veterans of 1st ed (and OD&D, too).
Seeing as there is a lot of SW:SE's DNA in 4th Ed, and the Skill Challenge system itself was retrofitted on to SW:SE from 4E, that probably tells Mike Mearls as much as he can meaningfully discern from our group's tepid reaction to the release of the 4th Ed of Dungeons and Dragons.
Sometimes, the reaction of D&D fans may be a genuine and informed reaction to the core mechanic of the game. In other cases, the reaction may be rooted in other marketing decisions which are beyond the control of a game designer. For now, our group's reaction falls in the second category. We just haven't given the game enough of a fair shake to be able to comment meaningfully on the game's design itself.
Other groups have other experiences which are necessarily different. I don't purport to speak for those groups. My comments are intended to sincerely reflect and deconstruct the reaction of the gamers/customers in my own gaming circle, only.