The Big 10 was good this year. The difference is when the Big 10 is good, the media amplifies everything Big 10. The Big 12 has had very powerful bb seasons in the past and never got the same kind of media attention and favorable tournament seeding.
It happens most years in FB and BB. Because the B1G is #1 in TV sets, the media automatically caters to them. All the media hype, convinces B1G fans that they are better than they actually are, and then the bowl season happens (or in this case the NCAA tourney) and they are brought back to reality.
Obviously it's more apparent in FB, where they are usually about the #3-4 conference and they get worked in bowl games. In basketball the hype is probably a little more deserved, but it's still artificially high.