But why? They already established Norrin Rad as the Surfer. I have nothing against women taking male roles in a normal progression but it just seems like they are doing it just for the discussion it will generate, not to make the story better.
I have yet to see a good answer to the question of "why" regarding this Surfer swap.
But to be fair, she did apparently become "a" Surfer for an issue in an alternate reality and then was promptly killed off. Additionally, her 5 appearances dwarf Norrin Rad's 744 appearances, so she is the obvious choice for the movie. /s