If brackets are truly fair, the Big 12 should only get 6 or 7 teams in. There's no reason that all three of Texas, Oklahoma and TCU should make the field. Similarly, both Clemson and NC State from the ACC should have some work to do to get into the tournament. I'd have similar questions for Minnesota, Ohio State and Indiana. Of those 8 major conference teams, I would argue that maybe 4 should make the field instead of all 8 (For me, it would be TCU, NC State and Minnesota only, but the committee probably picks more).
Being mediocre in a major conference should not get you into the tournament. Indiana is mediocre. So is Oklahoma. So is basically everyone in the PAC-12. If the PAC-12 wasn't considered a major conference, they would only be sending their champ to the dance.
It's time for the NCAA tournament to stop rewarding the mediocre teams in major conferences. I watched Murray State and Belmont on Saturday. Both of those teams looked like NCAA tournament teams (9 losses between them). And yet some major conference team with 13 losses will probably go to the tournament ahead of Belmont (the loser in the conf. title game). Mid majors and low majors only get two or three shots at good wins each year, usually on the road. Look at Oklahoma's road record against potential tournament teams - lost at KU, Texas, K-State, Texas Tech, Iowa State, Baylor, won at TCU. Didn't play another non-con road game against a potential tourney team. You can do this with almost every "bubble team" from a major conference and find almost no quality road wins. Why should Oklahoma get credit for going 1-5 against KU, K-State and Tech. NC State's best conference win is either Clemson at home or Syracuse at home. If you gave Belmont home games with UNC, Virginia, and Virginia Tech and road games at Duke, Florida State, Louisville and UNC, they would do no worse than 0-7, which is exactly the mark that NC State posted in those games.