I think if you're going to be working purely in the business world, like IB, Consulting, etc... then the business school strength is all that matters.
BUT
If you ever want to do something different, like in high tech, strategy planning in some big company of a different industry, entrepreneurship, off-the-beaten-path career, then sometimes the strength of the university comes in handy because either
A) People in your new field do not know b-school rankings well AND/OR
B) People in that specific profession see more credibility with a school that is strong in that professional area.
An example for B). If you want to do high-tech entrepreneurship or business development, then having a parent university that's super strong in tech (that's why MIT, Berkeley, and Stanford are so strong in high-tech business stuff) will help you greatly.
In the perfect world, I would pick a school that's strong in both parent and b-schools. Haas (for me) fits that criteria, Stanford did, while Kellogg might not, even though its b-school brand is stronger than Haas.
Sometimes I think my engineering degrees may come in more handy in what I'll do in the future than my MBA, depending on who I'm trying to persuade.
Just my 2 cents and my perception on how engineers in tech companies often view business people...