But look how they advertised the game. You only see the NCR Ranger Veterans everywhere you look. I didnt even know what the Legion or Mr House looked like untill I played the game (I didnt have internet at the time).
But Im not complaining. I like the NCR.
True. But I think that the NCR ranger was used simply because his armor "looks cool".
It might put players off if an image of Mr. House or a securitron was on the cover (and honestly the Legion's armor isn't all that impressive).
NCR gotta a lot of love in this game. Hell, I was shocked to find the BoS at Hidden Valley for the first time and they were shooting at me ! It was the midnight patrol I encountered.
I actually thought on my first playthrough that the BoS weren't in the game.
And about the Ranger image, yeah of course. They wanted to create an iconic image to represent the game instantly, so they made the vet rangers.
They did the same thing with the T-45d Paladin on the cover for Fallout 3. T-51b and MK2 power armor were iconic for 1 & 2, so they made the T-45d, because it would make sense that there not gonna have enough T-51b's for all the recruits they are taking in, and their T-51b's are probably falling apart from overuse so that's why you see no BoS wearing them.