ThymeLess, why are we to believe that what you say about a 3.0 at any Ivy is true everywhere? Despite your claim otherwise, it IS an anecdote where n=1, because you have served on far less admissions committees than there are med schools in the country. I'd be surprised if you'd been on them at multiple schools at all, but even so, 2 or 3 schools having that biased view in favor of Ivies isn't surprising. The point is there is no reason to think this widely held among schools.
Here's my similar n=1 anecdote: My university is a typical flagship state university, tier 1, football giant, whatever you want to call it, respectable institution, but by no means thought of as a powerhouse of knowledge. It wouldn't stand out academically from anyone else in our football conference, region, or the country in general. You claim that high GPA's at less than famous schools raise questions of maxed potential vs. maxed their school, but again, you don't represent the views of any considerable fraction of the medical schools in the country, and definitely not those of the Ivies. Over the past decade, my University has had various students go to Harvard, Hopkins, and other top med schools. I have no doubt that a high GPA from my school would have nothing but positive effect on my application.
Edit: If the issue is about lower "tier" (as defined by USNWR) schools causing a problem, that's different, and I would recommend people try to go to a "better" school (if only for the increased opportunities to be involved, likely higher endowment and chance for scholarships, opportunities for research if that's what you want, etc...) But the idea that there is this huge chasm between Ivy undergrads and the rest of the first tier is really exaggerated.