A lot of people think that the CCHA is top-heavy and the top teams have inflated stature in the media and in the Rankings because they play against lesser teams. Whereas every WCHA team is really solid and won't roll over . Thats kind of how I feel about it anyway.
The answer to your question is that people think the WCHA has more parity and that the top teams in the WCHA(UND,UW,UM,DU,CC, token MN team) are generally better than the top teams in the CCHA(Miami, MSU, Notre Dame, Michigan last year), therefore the top CCHA teams don't deserve all the hype they get.