Schools like BYU, Boise State, Cincinnati, UCF and Houston just don't belong in the Power 5 Conferences. They've had nice runs and can rise to the top of the Go5 conferences, but would just be dominated by the big state schools year after year.
Well, TCU, Baylor, Vandy and Northwestern don't really belong either but they're there anyway.
Of course as you may have noticed by the two hour halftime in the Championship Game it's all about money now, so symmetry or regional balance/rivalry don't matter much anymore, unless you can monetize it.