Like what the System said in his post:

Mostly because of Texas' getting preferrential treatment on virtually everything. Examples: recently the Big 12 title game being permanently moved to Jerry world & the 1 second fiasco from last years title game, the original alignment & interconference scheduling (Texas made sure they played OU every year but Nebraska vs. OU be ********ed), maybe the biggest reason - revenue sharing (league only splits about half of conference revenue among teams - the rest the schools pocket for themselves based on TV appearances). Big 10 distributes monies equally among all schools.

It's mostly that whatever Texas wants, Texas gets and the North schools are tired of it. Former Nebraska coach and current AD Tom Osbourne, who was against the Big 12 initially, has seen enuff. So did Colorado, and that's why Mizzou wants out too.

Texas' greed ruined the SWC and now they're ruining the Big 12. Seems there's a pattern there, so buyer beware.

crap, shows you what i know, i had no clue it was TEXAS' fault. i just like watching the games, hell with politics. maybe the change will be for the greater good then.