Re: employers and dress codes.
I used to volunteer to work in a local youth club. There was an implicit dress code. A suit would have been unacceptable. A "loud" T-shirt would also have been unacceptable. I was doing the children a favour, but in doing that favour I had certain responsibilities, and dressing appropriately was part of that. Compare golf clubs, night clubs, pubs, etc, etc.
It's good that people volunteer to work on Wikipedia. We're grateful for their hard work. But with that work comes responsibility. We ask that contributors check their facts and take some pride in their work. We ask that they collaborate with others. We ask that they behave civilly and with respect. Asking that they use an appropriate username is an extension of that, and not wildly unreasonable.
There is a middle way between unrestricted freedom of speech and "the tyranny of majorities who carry on like on-line lynch mobs" (nice turn of phrase). I think it lies in balancing an appropriate dress code with an appropriate means of asking people to follow that dress code.
-Martin "MyRedDice" Harper