You have no idea if those schools will schedule a home and home with IU. Maryland who is a bottom dweller in the Big Ten is currently playing a home and home with Texas. I agree it would be difficult, but not impossible.
Let's assume you are correct and IU couldn't schedule a tier 1 school from one of the other major conferences. There are still plenty of really good match ups that would get IU much needed exposure in the south and west regions of the U.S. Examples: Texas Tech, Baylor, Arkansas, Mississippi, Mississippi State, South Carolina, Oklahoma State, Georgia Tech, North Carolina, Arizona, Arizona State, California, UCLA, TCU, and etc.