I think the combat shotgun and the combat rifle look similar because they were trying to reference the Kalashnikov family of weapons and how adaptable they were. Going from single shot rifles to auto rifles to snipers to shotguns, etc.
I think it could've been executed better. (Having the Combat Shotgun be a mod for the Combat Rifle, to truly show off the adaptability of the weapon, while having the standard Combat Shotgun's place taken up by a different type of shotgun) But I don't hate what they did there.
What I do hate is taking away unique textures/models and just slapping a prefix onto randomly generated weapons. I fail to see how a rolling pin that gives me +15 damage if I'm addicted to something is legendary.
Hopefully, in a few years when mods have started to make the game playable again, there'll be something that nerfs the "legendary" weapons to just normal stat boosted weapons, and sticks in actual, unique weapons in the game world.
Grudge rhymes with fudge.