But the very idea of Superman really is him being on Earth. Wearing a cape and swashbuckler boots is based on Human fashion. There is nothing alien about that. Even when the idea of his suit being made from his Kryptonian blankets was introduced, its style was never based on Krypton fashion.
The 1978 movie introduced the idea of the Symbol having a Krypton origin. But even than Brando did not wear a suit that looked like exactly like Superman's. The idea of the suit being fully of Krypton design is very recent and I do not like it.
Take away the briefs and giving it more texture and detail does not change that it still looks like a human idea of how a hero should dress. All this over rationalization does not make the costume more believable or truly alien.