Despite being accepted to top engineering schools, I got mostly a full-ride to my local state flagship. To this day, I am not sure if it was the best or worst decision I made. I still made it to a top company without debt, but I have a feeling that any future education (e.g. a top MBA) is going to be hampered by this not to mention how certain things are basically excluded (e.g. venture funding, certain jobs).
One thing to remember is that a good percentage of those applying to top schools are coming from expensive private schools that are about as expensive as the university tuition, so to the parents that already paid 12 years of $70k tuition, 4 more isn't a problem.