The other reason is TV revenue. A 96 team tourney is too big for CBS to cover, and they would need help from ESPN to televise it all. Neither of those are good reasons for expansion to me.
But this piece by Andy Katz actually references an interesting point beyond self preservation and money.
Of course, I could be totally wrong, if the NCAA pushes through the idea that it already has 97 teams in the postseason (since it runs the 32-team NIT). The NIT television contract ends after this season, so that is still a curveball in these discussions. The NCAA could always do a bridge deal with the NIT and ESPN again to get it through the next round of negotiations for television partners in 2014 and beyond. (Emphasis added)The NCAA acquired the NIT a few years ago. An argument could be made that the NCAA doesn't need a second class tourney when it could make its members much happier by rolling those same teams into the big dance.
Personally, I think it simply dilutes the quality of the flagship product, but it's an interesting take. Apply that logic to the bowls and a playoff. You could easily see the NCAA starting with a 4, then 8 and then 16 team play off and then saying...."Well, we already have a post season for 68 teams (34 bowls), why not expand the tournament to 32, 48 or 64 teams?"
It's the same argument as the NIT take above.