portion comes from students paying 100k a pop to attend your university. So academics matter. When you start adding in the West Virginias or Utahs of the world, you are lowering the overall perception of your league.

I know that I am likely to get a better education at any of the Big 10 universities than I am at any of the SEC universities. (At least that's perception and perception = $$$)

The collaboration between research teams within a conference is a real and important thing as well.