I think it's better to not be a legendary prophecy hero and become a hero from scratch, and not because of some convenient power.
I don't think that any series should specifically stick with either one.
It's always nice to have a mix of these things, you don't want every game to be a simple "some nobody rises to glory through an unexpected chain of events" storyline
That was one of the greatest things about Dragon Age Origins, the ability to choose what your birth status is and then earn your blood status was awesome.