@Acolytus "But, but... muh dramas!" (^_~) More seriously, your point is completely valid... but what's a manga without some pointless angst, generally in the form of "My loved ones would hate me if they knew about X"?
Also, I suspect the drawback will be something like an adrenaline surge that lets you surpass your normal limits - you might be able to lift a car off your child in an emergency, but you also might hurt yourself and not realize it until later.
@Filuth @monstergelo I believe it's some of both, leaning more toward "a form of erotism". Black tights (which always look like they were spray-painted on, even IRL) are definitely more subtle than pantsu that look like they were spray-painted on, but they're in the same category.