Why is Ed the only one allowed to not wear the state uniform?

because he dose'nt have an offical ranking. duh do you even pay attention! besides he dosent look good in a millitary uniform XD

i think its because he isnt at an official army ranking. He is a state alchemist but he isnt a colonel or a major, so i guess he doesnt have to wear an official uniform. I remember in an episode of FMA brotherhood that there was a state alchemist who didnt wear the uniform, but he wasnt mentioned again because scar killed him.

Not all of the state alchemists wear the uniform I don't think Shou Tucker did and Kimblee didn't wear it for a while too. But most state alchemists do other military work which is why they wear the uniform.

I think it's because they had to distinguish him from the rest of the military, after all, he IS the protagonist!

Ed has a civilian status so he doesn't have to wear military garb also he is madami of a field agent and is usually on inspections and travelling, try wearing a uniform for that. Besides who would make such a small uniform. XD Hope I helped.^_^

Actually all state alchemists count as majors. They are all officially ranked but that have a choice to wear it or not they are not forced to unless a time of war comes.

He does have an official ranking and is technically an officer. He's just engaged in research and not stationed at headquarters, so he's free to wear what he likes. Same with Shou Tucker.