Because it matters but isn't the only factor. There are always lots of factors. First, it matters little to the B12, which doesn't have a strong academic rep as part of their image. So WVU was not much different than the average school in the Big 12. But remember that the ACC rejected WVU based on academics.
As for Louisville, in reading the details, the ACC thought that Louisville had rapidly improving academics, a strong endowment (more than twice UConn's) a high achieving athletics program in football, basketball and soccer, that brought in a lot of money and had a national brand. Then FSU reportedly threatened to leave if they didn't add UL. So they held thier noses and added a school that was worse than NCST, but which may not be worse for very long.
If university presidents are anything, they are snobs. Nobody in the Pac would even let anyone from Boise St. dirty their foyer. There is just no way.