ESPN is owned by Disney alias Evil Mouse Holdings. Disney is HQ'd in Los Angeles and is about selling entertainment. They homer for USC because that's L.A. and to Evil Mouse, L.A. and New York are the only America. They push their other anointed brands the Lakers & Kobe, the Yankees, Duke basketball, LeBraaaaaawn, Tiger, the hopelessly irrelevant Cowboys, and Tebow.
In ESPN's perfect world USC would play the Ohio St./Michigan winner for the NC every year. They cannot ignore the SEC although god knows they wish they could.
Bama is a top earner. They cannot be ignored. Evil Mouse is gonna sell these products as long as they earn and beat everyone else over the head with them. The Tebow stock appears to be diminishing. JMO.