Snyder did try to schedule some tougher opponents during KSU's prime years, most notably Notre Dame, but it was very difficult for reasons already noted... it took Pete Carroll's "we'll play anyone" attitude to finally bring a good team to Manhattan.
On the other side, does a team really have to play a thoroughly murderous schedule to be considered for a national title? Yeah, Florida nearly ran the table last year with the toughest schedule, but usually the team with the toughest schedule winds up being a 3-4 loss team who can forget even thinking about national title contention