I think it's a cooperative/single player game, and Larian is known for allowing unbalanced builds. It's only an issue if you care about it, and I don't.
Ok so your argument for, instead of nerfing the ability and making it similar in power level to other feats is:
Oh Larian does unbalanced shit all the time, so let's just leave it like that.
What?
And your argument is "I don't like this, so no one should be able to enjoy it."
Why?
When a feat is too powerful, and allows for builds that do 100+ damage at level 4-5, it limits other builds that are inherently a lot weaker, making for a worse multiplayer experience, and even single player in case you like making a lot of characters.
It doesn't really, though.
If the game is balanced around the other builds and this is just "massively OP" as you say, then playing other builds shouldn't be limiting in any way.
Say it is as OP as you say (I wouldn't know, haven't tried it), that's basically giving the player a button to go "instakill" on all opponents, as long as you play that one class and build. Doesn't mean you *have* to play that build to have fun in the game.
Just means there's an option to do that if that's what you want.