I've not played this yet, but is it possible to not have companions? I play solo in Fallout 3 and would like to do the same in NV (I play on PS3, so no mods/console commands etc).
Companions are 100% optional, although if you don't use them at all you won't get any of their quests, some of which are cool. I like the companions, but I don't use them all the time. Veronica likes to get herself killed when I have her set to melee. I actually don't mind that, though.
I'm playing with hardcoe Mode on, so trying to make sure they don't get themselves killed adds to the challenge of combat. If I can come up with a RP reason to have them along I think of them as being under my protection. I've even caught myself talking to them a few times.

"Get your [censored] skates on, Vero, we got company!"
Like I said, I don't use them all the time, but I'm a role-player, so I like to use them when appropriate because it adds to my character's narrative.