I think the BARS are for the punters, they instill confidence. Its not that they make you fly any better, but if 2 pilots were standing next to each other, one in shorts and T shirt and the other in a uniform with Bars etc, im sure the punters would sence more confidence in the pilot in uniform.
Oh and by the way if your gonna get new ones, make sure they are placed under the tyre of your aircraft and ran over a few times before you wear them.