I think the power system has something to do with it, but not in implementaion... More in presentation.
In the past we had classes that had various special abilities.
Like Barbarians got rage x times per day, and fast walk, and what not.
To me the power system is simply taking that concept, and letting he player choose what exactly the special abilities are. They aren't set in stone before you design your character.
It's just because they're labled "powers" and presented in easy to use spell like boxes that makes them seem like something new in my opinion.