Because it doesn't limit your options at all. There's a lot of viable options if you only look at women, much like a large, large number of your favorite movies had a lot of viable options available to their producers when they only looked at men. That particular practice has been ongoing since the industry took its first fuckin' steps, really.
Your inherently sexist argument only seems to crop up whenever someone suggests they'd like to see a woman in the director's chair, which kinda says something. You're apparently a-ok with a whole raft of male names getting shot like spitwads at fandom's chalkboard, but when someone suggests maybe pulling from a different talent pool suddenly it's a question of lost potential?
Nah.
If anything, the potential of the movie getting made and made well likely goes up if you look at that female talent pool and pick a creative with the particular eye to make the ending of Rey's story emotionally resonant in a way a large number of men just don't have the perspective to carry off.
Hell, Abrams himself knew enough to know he needed to run TFA past Ava DuVernay before he finished the film.
