Position is very important. If you are UTG with AQ and raise 3x the big blind and then get blasted from a guy in a later position, what do you expect him to have? I'd say something better than AQ. However, if you are in late position and some raises 3x the big blind, you can feel confident about reraising for two reasons: one, you'll have position on the later streets.
two, if he comes over the top on you, then you have a better picture of what he is holding.
It takes a better hand to call a raise than it does to make one.