But in the TV shows, we could argue that Starfleet marines wear the same colors as Starfleet sailors do - all three of them. After all, we already saw marines (whatever their name in the ST universe) in episodes like "The Siege of AR-558", and while their uniforms were distinct, their colors were the usual red and yellow (and perhaps blue as well, although that was not actually seen in any episode). Marines would have their own fighters, engineers, medics and surveyors, just like the sailor branch of the organization does, and would need all three colors.
I agree. While I like the idea of Starfleet Marines (or whatever they are called), I don't think there is enough support in canon for such a thing. Doesn't mean I didn't used them heavily in my own role playing games or fan fictions, for example.
I hope ST XII introduces Marines. I've always wondered what they would have been like in TOS' time. I think they should wear the standard TOS style uniform, but in BLACK
(meaning, a black uniform shirt as opposed to a red, gold or blue one)