Thing that always gets me about these arguments, is they are always based on the premise that the good school predates the expensive area, in our town at least, the houses near the 'good schools' are more expensive, but then they are bigger. The poorer schools are near the smaller, less desirable properties. The school is only 20 years old, the houses have been there since the 30s, it's always been a 'nice' end of town.
The assumption seems to be the school's performance isn't due to the sort of people who live in the area and send their DCs there, but somehow, miraculously, the good schools have all ended up near big houses and the rubbish schools have ended up near the smaller, less disirable ones.
I don't believe the good/bad school can be divorced from it's catchment. Do you really think that if the school staff were all relocated elsewhere the school would be exectly the same? If you remove the link between the school and it's area, do you think the results would be the same?
Also, it rather assumes school is just for education. There's the social side too and if you live several miles from your classmates, play dates are harder, playing with friends from school at the weekend not just being walking round the corner, but needing your parents to drive you 5 miles across town and back stops it being something that can happen every weekend.