The cool things done with the nudity include:

• Karlach's chest glowing from the Infernal Engine she uses as a heart

And that's it. They're not particularly good looking or anything. Other than Karlach, the nudity is quite generic and unsexy.

I feel like having full nudity is just a cheap gimmick that doesn't add anything of value. The only mainstream game I've played that even uses nudity as a mechanic to do something special is Elden Ring and you're not even totally nude in that game.