Qualified yes. It provided a powerful tool for showing the flaws with previous generations' research and, when used properly, can supplement older texts without destroying what made them valuable in the first place. I'm thinking of Joan Scott, at the moment, especially her essay about E. P. Thompson.
Most postmodernists would argue that when used for such purposes it is
not being used properly.
I think you have a point though; personally I detest it, but it does mean that historians have had to think about the theoretical side of their work (and theory is unavoidable in an abstract discipline) in order to attack it which, in turn, generally leads to better work.