It would be just an immense improvement, if they would simply allow males the female animations and vice versa.
With all the clipping issues already i don't mind temporary ones in anims, but that my male character can not salute or wave is weird. also why can't females not get the male danglfeet one (and vice versa)?
Another option to earn money would be to add stances or looped animations (ideally you would have one basic stance affecting all the other doable anims, for example male_drunk, female_exhausted, etc.. they already have it to some extend with the "sit" stance).
Some part of this can be done easily others would require new animations or at least some coding. But back to the shoppe: Once they sort this, they could make female_standard for example the default one and then start selling stances and emotes (or add them over time due to festivities, events, quests etc.). And if they are costwise far under the amount a premium gets for "free" every month, they would add more value to subs while still able to make something extra from f2p.
About "no one would buy"...this is highly subjective, but i agree with you that some would become pretty popular...be it dances or more rude stuff.