What do u use companions For.........
Suppport
company
Pack mules
ETC.
So what do u use them for...............

I use them to make me feel more "Awesome" I guess. It's enjoying to enter the Duper Mart and have an epic battle "Companions Die" (So company would be one I guess since they "Always Die")

I mostly use them as pack rats. I'm almost always near overweight or would be without companions.

I like to play my one trader character and his pack Brahman. Its just him and his Brahman to wonder the wastes. It's nice to fight alone and scavenge the wastes for anything to stay alive.

I really like having Fawks walking into the Citadel. I imagine all the BoS getting their panties in a bunch. Of course, It doesn't really happen, but the whole game is about "what if. . ."

Once in a while Fawkes would say something like "It's interesting that they don't attack me when I'm with you." I really like Fawkes' character, because unlike Fallout: NV with a number of intelligent super mutants, Fawkes' is really unique in FO3.

Another aspect, apart from those mentioned above (company, support, mules, etc.), is the concept of the Lone Wanderer walking across the wastes. I imagine the devastation and disconnection that people would have in a land full of creatures that want to kill them. So depending on the play through setup, the Lone Wanderer may bring a sense of order, and having some really interesting (different/odd) companions would tend to elevate the Lone Wanderer to mythical or legendary status.