Their uniforms have some temperature controls per dialog in TOS.Kirk looking like a 19th century soldier is at least a bit odd, surely.
I'm not sure why one needs all that heavy wool on a climate controlled ship. Especially when the thing only gets hotter when the climate control stops working (as evidenced by the sweat pouring off the good Admiral in The Wrath of Khan).
I rate the maroons highly but them looking like a military uniform is not my objection.