Just my two cents worth. I don't know why the FTOs choose to require uniforms, but I do suspect that there is reason behind it (which I don't know) given that they all do it.
However, that's not my major point. I find it VERY confusing that so many of you are so opinionated on the subject. Is it really worth giving yourself an annurism over? Probably not.
Personally, I'm agnostic over wearing a uniform. I would happy not wearing one, but I'm just as happy to wear one. It really doesn't make any difference to your ability to take or pass a course to gain your fATPL or gain employment at the end of it.
However, in the grand scheme of things uniform/no uniform is pretty petty, isn't it?