jallenmorris
Why do people not want to stay their UG school?
did you mean "stay at" their UG school? or did you mean something else? if the former, I'm headed back to my UG school because I truly enjoyed my UG experience there (and it's a great b-school in itself, fitting what I want to do).

As for the "debate" going on, I have a theory I don't know if it's actual fact or not. Since there are WAY more applicants than seats at the top 15 b-schools, and hypothetically saying that all the "top applicants" (the ones that have demonstrated great leadership, GPA, GMAT, etc...) come from a good spread of schools, if you were the adcom, how would you pick between people of similar GMAT, similar GPA, and similar career progress/leadership/extracurriculars? Would you lean ever so slightly for person A from Harvard/Princeton/Yale (and Berkeley, yay!

) or would you pick the person from a respectable non-top-50/100 school?
Granted, the adcoms want to keep diversity in their minds, and will probably pick a non-top-50/100 school applicant (all else being equal) once in a while, but a top-50/100 school is in the top rankings/reputation already did the pre-filtering for the b-school (with their own very stringent admit process), so having a UG degree from those schools itself is a "stamp of approval", similar to why we're all trying to get an MBA from a top 15 school.
I personally believe that is the reason why many of the top 15 b-schools will have mostly top UG students, with a sprinkling of other good schools here and there because those applicants maybe did some spectacular things that were better than most top UG applicants... It's a natural conclusion when you have lots of competition between very similar backgrounds, and one of the few differentiating aspects is your UG degree and GPA.

BTW, as a liberal arts major, all the Ivy + Stanford are definitely good schools, but don't forget if you do sciences or engineering, MIT, Berkeley, Cal Tech, and Georgia Tech comes into play as a UE school. Actually Berkeley is highly ranked in all the liberal arts majors too, generally in the top 5.