You lack imagination about all the different things that can be done with uniformly black, straight, fine hair. Length is not the only variable, and there is still a huge range of hairstyles that people could choose from if they were free to do so.

Also, if I was subject to an edict requiring me to trim my fingernails, that would be a pretty big deal to me. A big, intolerable deal. You imply that from their perspective it wouldn't be, but are you so much of a cultural relativist that you think such a perspective isn't seriously unhealthy?