First, the entire development, playtesting, and release of 4E and the retirement of 3.5 followed a profit-making corporate model to the letter. Think about it: WotC first pulled all 3.5 stuff off the shelves, thereby eliminating the one source of competition for 4E that they had control over, not even bothering to offer eBooks in pdf format (which would have required next to no overhead). During development, WotC tested two products: one was released first as Star Wars Saga, the other would eventually become 4E. WotC went ahead with 4E and stopped supporting Saga, even though Saga garnered more points from playtesters. Finally, WotC released the Core Rulebooks and started releasing supplements, along with a promise of online content. Oho, but it turns out that the online content has a price, on top of whatever the books cost. And, double oho, errata and rules clarifications aren't available anywhere else. A gamer on another forum compared the 3.5-4E switch as the Old Coke vs New Coke of RPGs...except that in this case the manufacturer managed to totally disenfranchise the fans of Old Coke, and have no intention of trying to win them back.
Now, take a look at game mechanics. Look at how many character powers refer to moving/shifting. These powers make it exceedingly difficult to keep action in the mind's eye- it begs for miniatures and battle maps. Miniatures and battle maps that WotC is more than happy to sell, of course. Can you play 4E without all of this? Surely. But if you want to play an RPG without spending tons of money on supporting products, you might as well stick with 3.5.
Summary, Part 1: WotC's actions in developing, releasing, and marketing 4E and its actions in retiring 3.5 are purely profit-driven decisions.
It took me a long time for me to quantify what 'just felt wrong' to me about 4E. This criticism had nothing to do with corporate greed; it just felt like 4E doesn't have a gaming heart and soul. My gaming group often plays board games as a break from gaming (especially if a DM needs some time off for whatever reason). I suggested 4E, since it's just another board game. Hell, to me even World of Warcraft is more an RPG than 4E is.
Then I came across an excellent article about the three different styles of gaming as they apply to 4E ( mxyzplk.wordpress.com/2008/06/12/is-dd-4
I think another thing that turned me off from 4E is the game world. It isn't Forgotten Realms, Greyhawk, Mystara, Planescape, or any other setting I'm become familiar with over the course of 25 years of gaming. I think it's Eberron, which even in 3.5 I regarded as utterly unnecessary. Nothing about Eberron appealed to me or seems to bring anything new to the table. This is just a personal preference, but the point is, this fact makes 4E seem disjointed to me. Its a game without a setting- again, just like a board game.
Now, here's the Big Disclaimer to All the Above: I have not yet played 4E. Given the opportunity, I would try it...but I'm sure not going out of my way. I suspect that I would enjoy it quite a bit if I wanted to play a board game... or a tactical miniatures game.
Summary, Part 2: from a mechanics standpoint, 4E seems to marginalize 'simulationist' type gamers like me. I'm sure you can role-play in 4E, but that seems to be a secondary thing, not anything that the developers tried to conscientiously include.