If we had the art resources to make unique textures and/or unique models for every weapon, we would have made unique versions of every weapon. I think it's important that if the player finds a unique version of something, it should look different than the base version. That's also why most of the weapon mods are externally visible.
That said, the Gatling Laser has been increased in power for the next patch so hopefully it will be more generally valuable instead of an anti-tiny-critter weapon.
If you can't do it by yourself - cooperate with community. Modmakers will be happy to help. WME or WMX - they have much more useful mods than original game.
Energy weapons have a big problems with uniques. AER14 Prototype could be nice as energy sniper weapon, but it can't be scoped, and without scope it is clise combat weapon only, and in close combat Q-35 is much better. Pew Pew? Another useless thing - eats ammo in tons and useful only in close combat. Plasma Defender is much better. Tesla-Beaton Prototype - another strange thing. Maybe deathclaw killing who can't get YCS/186 because of perk. Ok, YCS/186 and Q-35 are not bad.
Where is unique Plasma Defender, main close combat energy weapon? Where is unique RCW, energy SMG? Where is unique Flamer? Instead of them we got tons of unique close combat weapons and low level junk, which will mostly never used. Only really useful low weapon is Ratslayer (at low and middle difficulties), sometimes Lucky.
Guns? Maria - 9mm pistol, which you can get at the end of game. Just a trophy, useless. Vance's 9mm SMG, same. This Machine, mostly useless without scope, but good weapon for Boone. Gobi Campaign Scout Rifle is really unique. It is WEAKER then normal. That Gun? Mostly useless. La Longue Carabine? Have
10 times larger spread than usual version. CZ57 Avenger? Have very limited use.
Where is unique Anti Materiel Rifle? 12.7mm SMG? Trail carabine? Brush gun?
TL;DR: there are a lot of unique weapons, but most of them are low but obtainable late in game and useless because of that, or have major issues and useless because of them. And most useful weapons have no unique versions or they are worse then usual ones.