[Sunstrider]

I think that the fact that we don't see explicit female werewolf (or other monster) transformations can be attributed to several factors.
Mainstream audiences consider something as harmless as hairy armpits or muscles in a woman to be incredibly unsexy or just plain gross. Even if you had Jennifer Lawrence, Scarlett Johansson or Kate Beckinsale as protagonists; a producer feeling grossed out could turn something fantastic into a quick, 2-second crap-tier CGI scene.

It also involves nudity.
Imagine a female-led remake of an American werewolf in London. I don't think many famous actresses would accept to do such a movie in this current age. How much would be altered to avoid being considered sexist or to fit the personal terms of an actress not willing to do nude scenes?
And direct-to-video movies while willing to take more risks, they suffer from smaller budgets and limitations. Even Hyenas avoided full nudity and abused CGI instead or recurring to prosthetics and makeup to fit their limited budget.

Remember that movie with Judy Greer playing a she-wolf trying to kill Christina Ricci? The last, awful Howling movie with the school kids? Chloe Moretz in Dark Shadows?
Female werewolves these days mean fast and cheap CGI, growling, glowing eyes, long fangs and claws. Or just plain girls acting like dime store Wolverine knockoffs.