A band T-shirt is a bit different. It's a very normal item of clothing with an image or slogan on it. I've got a couple of band T-shirst, but I'd never wear a football shirt (unless I was playing football of course). If you were to go and watch The Darkness in spandex I'd accept the comparison...
Each to their own, but if I went to a watch a western at the cinema I wouldn't wear a cowboy hat and poncho. If I went to watch tennis at Wimbledon, I wouldn't wear white. If I went to watch boxing I'd wear a top. If I was performing neighbourhood watch i wouldn't wear a policeman's. My son...