And the little tidbit that West was named after an actual Marine (Oliver North - get it? North? West?
) doesn't exactly hurt either.
I just LIKE the notion of Starfleet having Marines, that's all. It seems like the simplest option. They may have different ranks, and different uniform colors (in my headcanon, the Marine color in SNW/TOS is black, and in TNG and future eras, it's light gray), but they are still Starfleet, and would probably be rather offended at being regarded as a separate service.
The Starfleet navy flies the ships, the marines are the boots on the ground. Like I said - easy peasy.

I just LIKE the notion of Starfleet having Marines, that's all. It seems like the simplest option. They may have different ranks, and different uniform colors (in my headcanon, the Marine color in SNW/TOS is black, and in TNG and future eras, it's light gray), but they are still Starfleet, and would probably be rather offended at being regarded as a separate service.
The Starfleet navy flies the ships, the marines are the boots on the ground. Like I said - easy peasy.
