It's hard for me not to view new editions of D&D with anything but cynicism. I'm sure the game designers are earnest in their desire to create a better experience, to provide people with the best game they can manage. But as a company, WotC is driven by the need to make money and as you (Greenfield) suggests, you have to figure WotC is looking for something new and shiny to sell.
What pushes me over the edge of cynicism is the method in which WotC has gone about it. 3.5 is still very popular. But rather than service its existing customer base, WotC abandon them and refuses to answer any questions or provide any support for 3.5. WotC published a ton of splat books fro 3.5. People spent a lot of money buying 3.5 product. But as soon as WotC moved to another edition, they dropped all the 3.5 players like an ex-girlfriend. You have a questions about rules in 3.5? Too bad, buy 4e.
WotC has convinced me that they aren't really interested in what's best for the gamer, they're interested in profit. The problem is that most companies don't understand that the relationship you have with your customers is crucial to profit.
I'm not interested in supporting WotC with the attitude they've displayed. If WotC refuses to recognize my needs as a 3.5 player, I'm very happy to play a version from which they generate little or not profit.