Fallout brotherhood of steel had plasma cannon.
So yes, im all for it.Also plasma weapons should be same as in fallout 3. They should be high end weapons, not pistols with green bullets like they did in new vegas.
The ones in Fallout: New Vegas, the Glock 86 and the Winchester P94, are the same as in Fallout 1, Fallout 2 and Fallout Tactics. You don't like them bringing back the old-school weapons? Personally, I think it's weird how all the weapons already established in the lore just vanished like that, I mean, where are all the Wattz weaponry? The Wattz 2000 is much cooler than what we have now. I hope they bring it back and maybe make it a sniper laser rifle or something, since it looks more like a long range weapon than that boxy thing.
Edit: I also wish for Bethesda to make the deaths by energy weapons cooler like in the old games, it's pretty gay like it is now, one of the main reasons I don't use energy weapons. A pile of ash, a pile of goo? Sigh... I want a laser weapon to cut off limbs like a hot knife through butter, like in Fallout 1 - cutting off the person in the middle by the waist. I want plasma weapons to melt a person in a pile of... BLOOD AND FLESH! Not green, shiny goo like it was a vampire from Twilight or some ectoplasm from Ghost Busters. It's more like the http://www.youtube.com/watch?v=FftEeQmuDWM&feature=fvwrel but faster. It's much more brutal, like Fallout should be. Death scenes are a bit childish right now as it is. I also want the death animation of the burst fire mode from the old games, it's the most satisfying experience in any game ever. The sound of bullets ripping his body apart as he gives away a guttural scream, seeing his arm and his head fly off and his broken ribcage sticking out of his side. In that way, the older games have much better graphics than of those today, it doesn't satisfy me as much killing people when their bodies just bump around and fall in awkward positions as ragdolls..