Oh various things really. We're totally off-topic, but the biggest one to me seems to be the complete redesign of the game itself. There's nothing in the data to suggest that the sweeping changes made from 2nd ed to 3.0 were really needed at all. Most people who "lapsed" in the game did so primarily because
A they got too busy,
B didn't have enough time, or
C didn't have enough people to play with.
Additionally WotC seems to have ignored the fact that its own data suggests that its "whales" are those that have been in the hobby the longest. Every grognard that they alienate costs them some $2500 a year in lost sales. Also, the real fans of the game and those who spend by far the most money are all adults and for the most part DMs. Perhaps it's just me, but 3.X seems obsessed with giving 'Players Options" and is clearly aimed at the younger, video game crowd; considerably more so than any of its predecessors.
There's quite a bit more, lost opportunities and the like, but you can check it out yourself if you'd like:
http://www.theescapist.com/WotCsummary1.htm
Look, I don't want to start an edition wars or anything, but most of the major changes (or at least those that many of us grognards complain about) were things that Skip & Monte thought would be good for the game and had absolutely nothing to do w/ the marketing research. There seems to be this notion that everything about 3.X was designed as a "response to what players wanted," and that's just not true really.