My dad is an emgineering consultant with years of experience in the field. He has told me that the simple truth is, if he gets 30 resumes for an open engineering position, the people who go to the top of the pile and are most likely to get an interview are the ones who went to schools like MIT or U of Michigan. He's playing the odds- he knows those schools recruit the brighter, more hard-working kids, as a general rule.
Same thing in other careers, such as law- having a certain school on your resume will, at the very least, keep your resume from immediately going in the trash.