A non-obvious benefit to energy weapons: Ammo has high compatibility. Your gauss rifle, Q35 and multiplas all use the same stuff! So you have a sniper weapon, a mid-range all around weapon, and a shotgun that all draw from the same pool of ammunition, unlike if you had the Guns equivalent of each weapon where you need to carry ammo that can only feed ONE of them and is wasted inventory space if you don't end up using it.
I agree that energy weapon ammo is pretty heavy, but it does have other benefits.
Also consider that Energy Weapons has the only ranged weapons in the game which do not require ammunition, which can help you save some weight. Recharger pistol weighs 7 units, or, 70 rounds of MFC ammo. But it's good for hundreds (thousands?) of shots before needing to be repaired.
That gives even more reason to reduce the energy weapons weight, since alot of weapons use that ammo, you need to carry THAT much more of it, and when that ammo, Microfusion Cells, weight 0.1lbs, it makes it that much harder. In 0.1lbs you can carry 1 5.56mm , 1 .357, AND 1 .308 round. I dont need to go into how many weapons use that type of ammo.
As for using recharger pistol, at very hard difficulty, the geckos outside goodsprings will eat you like a donut if you decide to use that pea-shooter on them. Im not complaining about how hard the difficulty is, i am managing it just fine and enjoying it, i just feel that EW ammo should have weighed a little less since i need to be carrying a heavy punch all the time and loads of it. I hate fast travelling to safe house every 10 mins. Kills the immersion.