We wear them because the company says we have to. Show me a large feeder out there for FedEx, UPS, etc. that doesn't wear uniforms. You bank pilots can look like your redneck, trashy couriers all you want and nobody cares, but there is a lot more $$$ at stake in feeder flying, hence the need to look professional.
But hey, it's your lucky day. I've helped more than a couple people from this site get interviews, jobs, bases, and equipment choices, but I
promise I won't do a thing to help you out if you even were genuinely interested in coming here. That way you won't have to wear one of our silly monkey suits or fly the lowly Be-99. How's that?