Dave Martin,
Uniforms are a part of our culture, and therefore are a part of our life. When at work, you are representing your airline/company/sports team/etc., and I think you dress accordingly. You don't see footballers dressed in jeans and t-shirt when they are representing their club. They wear their kit/suits/clubs products.
Wearing a uniform does not detract from ones ability to speak up. That's the biggest load of cr*p I've heard. Wearing a uniform does not make you a conformist, but what's wrong in taking pride in your appearance when representing yourself and your company.
I doubt that airlines judge their candidates by apearance alone! If they did, they'd be hiring models. I disagree with the argument that women could be kept out of the cockpit based solely on their dress standard, maybe in the past there was a prejudice, but things change.