I would go even further and say that 4e was designed for people who also didn't like the mythos that had grown around D&D either (which pre-dated 3e)... 4e not only had many mechanical changes but it also changed the default assumptions of the D&D fluff.
This was, IMO, a big mistake on WotC's part. By doing this they alienated two subgroups of players... those who liked the mechanics of 3.x and those who enjoyed the default fluff of D&D... In other words they invalidated not only the system mastery some had gained but also the mythos knowledge others had invested in. I think they would have been served better changing the mechanics with this edition and keeping the default D&D mythos... while putting the changes to fluff in an optional campaign book. This would have allowed them to assess just how popular their fluff changes were with DM's and players... and if it proved more popular... then you make it the default.
On a side note, I find it ironic when people who don't like 4e are told to "Just find another game instead of wanting D&D to be something different" because, IMO, 4e came about as a way to try and appease those who really weren't happy with the mechanics, conceits and fluff of previous editions.
There has been a tendency in 3.X/Pathfinder gamers to say that 'WotC misread their audience'. Nowadays I am more of the opinion that WotC read a
portion of their audience very well, as evidenced by the strong defense of 4e by its fans.
The question is more one of how much of their audience it was that they were reading, and if they believed that the stragglers would fall into line and buy the new edition, despite their misgivings.
The announcement of Pathfinder changed that last - there was less need to try the new system, and even less to play it even if you did not much like it. There is definitely enough interest in something closer to the 3.X rules than 4e to keep Pathfinder rolling merrily along.
However, because there
is Pathfinder it is unlikely that a D&D 3.75 by WotC would gain much traction, the audience has moved on, as has WotC itself.
At this point, I think that WotC and their fans are better served sticking with 4e and whatever directions that leads them - the market is split, trying to turn back the clock is doomed to failure, and, this is important, there
was a vocal percentage of fans that did not love 3.X. It may have been a majority (I doubt it, but it may), it may have been a plurality, or it might have been a large and vocal minority (my bet, plus a lot of fence sitters who didn't/don't care much either way).
But Pathfinder meant that those folks who preferred 3.X had someplace to turn, and those who are comfortable on the fence could stay there, even,
gasp! playing both games!
So, the market may have split, pretty much because there was not much reason for it not to do so. Games are available for both audiences, and with Osric, Hackmaster, etc., more besides.
Which is selling better really doesn't matter that much - locally it is Pathfinder by a comfortable margin, but I am certain that there are other places where the opposite is equally true.
The market probably
is split - I don't think that there will be a winner (except the darned fence sitters - they get to enjoy the best of both games, dang their hides!) The audience will need to adjust, because while there are no real winners, neither does there need to be a loser.
I think that both games are here to stay, even if 4e becomes 5e in two years time.
The Auld Grump