First off, I must correct you on something...
Cornell is an Ivy League school, they don't give athletic scholarships....it's against Ivy League rules (which in many cases is separate from NCAA rules).
Second, as much as I am a supporter of the NCAA, I believe some of their rules are downright ridiculous, such as the opt-in rule.
In answer to the thread's original question, some very good answers were given but I'll add a bit more.
Someone mentioned the four "major" conferences (CCHA, ECACHL, HE and WCHA). Even within those conferences there is a wide spectrum of talent. UAA for example can't draw the elite talent (or as much thereof) as say a Minnesota or UND in the WCHA. Some will say the reason is geography, others will say it's money and so on.
There have been and continues to be cases where there are players that seems to have come out of nowhere who become great collegiate players, Scott Parse out of Nebraska-Omaha is a very good example.
What people forget is NCAA players are STUDENT-ATHLETES. Hockey isn't the only thing that's going to allow them to play in the collegiate ranks. They also have to be able to have the "grades" to play. Keith Yandle, who now plays with Moncton, originally had intended to go NCAA. UNH, where he originally wanted to go wanted him playing a year of US junior "A", so he opted to change his destination to Maine. The Black Bears really wanted him to play this year but he didn't have the grades to get into Maine, so he ended up going to the CHL. The academic standards are even more rigid for players desiring to go the Ivies. At schools like Cornell and Harvard, you can't just be a good hockey player and expect to get in, you have to have a very strong academic record (grades) as well.