Eh, well, most animators (and writers and whatever) these days are still male, so it's understandable.

Herein lies the problem itself. Why SHOULD it be understandable that males shaft female leads or characters? Why does modern society still push and reflect values like 'females are not made to be heroes or main characters?'

I don't think institutionalized sexism should be cast off as just 'understandable' when it's a problem that needs a'fixin', and I believe that's what 129's OP was suggesting.