When families look to move to areas, one of the very first things they do is check out school stats. And more affluent families then make the decision to settle in the suburbs, where the schools are "better" (which usually means lower student/teacher ratios, higher graduation percentages, etc.).

True--although if one is weighing the balance between Cost of Living and Quality of Life, it might turn out to make more sense to buy in an urban area and send one's offspring to private school. And in my [urban residential] neighborhood, there are families who do just that. (It is worth noting, however, that the families sending their kids to yeshiva probably wouldn't consider a secular public school no matter how highly-ranked).