i think dressing up is an integral part of being a performer. essentially, performing is pretty much a visual thing as much as an aural experience for the audience. Gerard Way of MCR once said in an interview that he thinks that aspect of a performance is as important as the music. they really went for the jugular and the result, a very distinct image, easily recognisable and associated with their music. it gives their music a "face" so to speak. and i think it's pretty effective cause it certainly does leave a lasting impression on you.
if you look like everyone else, it'll be harder for you to be recognised i guess. after all, the dominant sense of the homo sapien is sight. so the first thing people will commit to memory about your band even before the first chord is played is what you look like. subconsciously it leaves an impression.
a recent and local example would be Live The Dream's, By Definition (if any of you watch that show). they're a prime example of how dressing up well, and being coordinated has it's benefits. i feel that they easily stood out, and combined with their energetic performances, they gained a fanbase. i'm not a supporter nor did i consistently follow Live The Dream, but that is testimony to the fact that dressing well, helps you to gain a certain image and gives a level of recognition. oh and i think that band won the damn competition!
so pull on the threads softies!