>>278961658
It appeals to those people in particular because it allows them to have new interactions with regular game objects. A gun in Gmod is either just a view model that spits out bullets or a prop that spits out bullets while you awkwardly try to move it around with the physgun/whatever it's attached to. A gun in Boneworks is flexible; It's a regular gun, a gun you can hold like a retard, a melee weapon, a makeshift stilt, it can hook onto things, it's a throwing weapon and because the AI is shit it can also be a tripping hazard. You'll know if you're the kind of person to enjoy those extra interactions if you find yourself using the barrel of your gun or end of a melee weapon to tip the trash cans over rather than walk up to them to look inside.
Where it's lacking is everywhere outside of the basic interaction. The enemy variety is very poor, the level design is bland and it leaves out too many standard game conventions that could have been fun like the explosive barrels >>278962869 mentions. To top that off, mods won't be making up for it.