That has been my thinking on full suspension cars ever since TCs first started getting popular. I remember taking one of my TCs and swapping the hard front springs witht he soft rear springs and could not tell a difference. In these cars it seems tire selection is critical.

However in pan cars running foam tires there are very noticable difference in springs.

I haven't yet figured out if my observations are because of the difference in properties between foam and rubber tires or the difference in suspension design.