Can't blame it entirely on casting a woman as Frank...
Even if they had cast a man as Frank, if they had done everything else the same, it still would have sucked. It still would be a sanitized, G-rated, over-choreographed, high school version of Glee.
They could have made it work with a female Frank, I think, if they had swapped everything. For example, made a muscular, beautiful female Rocky, had Janet as Frank's primary object of conquest, etc. Oh, make Frank a drag king while being happily female, like Curry's Frank was happily male.
They would have had to add the edge back in, the grit. Add the sex back in and make Frank intimidating again... give him (or her) his edge back. In the original you never quite knew whether Frank wanted to have sex, kill, or both. Then probably do something with the corpse.
In the new version, the worst you had to fear from Frank was a bad word or slap on the cheek.
And a pretty Riff Raff? No! Give me back the creepy effer Riff used to be, the bisexual Transylvanians, and a cast NOT composed of stereotypically attractive people.
Basically, do a full gender swap and rough it back up.