"Wah. look at me; I'm cool; I hate and bash pretty"
Some of your guys lack of imagination is disgusting. There could probably a thousand legit reasons for a sligh difference in gender appearance. Dimorphism is already stated. Another reason: Male Remans just go out in the poison all the time to do the hard disfiguring stuff and keep their females in protected enviorment.
I'm sure there will be enough options to uglify characters for everybody that wants to.