To an extent you're correct. Here's my thoughts:
1. The vocal fanbase that is upset is not necessarily correlated to a loss of sales. Certainly it's resulted in a sales loss to some repeat customers, but whether or not that's anything more than a drop in the bucket is unknown. I don't like all of the 4e changes, but I didn't like many of the 3e decisions either. I still bought both 4e and Pathfinder and I'm willing to bet I'm more in the center of the demograph of older gamers that WoTC is looking for than the people that are complaining.
If peopld are just complaining but still buying books, then there isn't a priblem. I suspect you are wrong though. Lots of us are not simply complaining but haven't been buying their books as well (and I think this was part of the problem 4E encountered). Clearly WOTC has lost customers that they have gained that many new customers seems alot less clear to me.