It goes beyond that. Many of the elements of the story were taken more-or-less directly from the canceled Van Buren game back in 2003, which saved them a lot of writing.
Anyway, none of those points are very good. The story is not 'branching' in New Vegas. It's pretty much identical regardless of who you side with, aside from a few side missions that re-use areas. 'More weapons' doesn't mean anything if they're not fun and properly balanced, which they generally aren't. (Which Sawyer himself commented he was unhappy about in NV.) And saying 'more factions' equates to a better story is as silly and stupid as saying 'more characters' leads to a better story.
Well in the battle of "more weapons but unbalanced" vs "less weapons but still unbalanced", the one with more weapons wins because at least I have more variety in how I overkill things.
More factions or characters doesn't make the main story any better, but they do make the game more interesting to play when you have more interesting characters and factions to play with. It's why Mass Effect 2 is so good, because of the characters that you're with.
Although they also misrepresented that one. Even if you don't want to count every town as a faction, they still missed the Outcasts and included the Enclave as New Vegas faction which is pretty weak considering they're like 5 NPCs and 1 quest.
There is a lot more endings you can get in New Vegas that come as a result of the choices you make during the main quest, though I don't personally fault Fallout 3 for that because I don't ever play to the ending of the main quest in NV anyways on account of it ending the game and preventing me from playing any more.