That's like saying 'Nobody ever seems to be able to state a rationale for making it in the color red, beyond they like red things'.
It's something people are going to wear. They want to adorn themselves with things they like. Period -- end of discussion. No other rationale needed.
Actually, it isn't at all like that. A stoplight is red not because it's a pretty color but because it has meaning. It would be easy to come up with innumerable other examples of why things are shaped or colored as they are. So, no, your inability to provide a more sophisticated answer does not end the discussion.