I think the director and writers are more to blame than Finn. They wrote him to be a boy in a man's body with ancient wisdom and petty aspirations to run a billion dollar company. Alot of contradictions and I don't think any actor could get a grip on such unintentionally conflicting ideas in one character.
It made him unlikeable and you end up rooting for the people he comes up against... Madam Gao, Bakuto, Harold, his friend from Khun Lun, etc all are more straight and narrow whereas Danny Rand is a mess of a character.
Also, does every hero have to have this "to kill or not to kill" struggle?
The Avengers kill with impunity and no one bats an eye but we come to these shows and Daredevil, Jessica Jones, Luke Cage, and now Iron Fist all have deep struggles about killing someone who clearly deserves to die. It's a tired trope. Luckily, we have Punisher who doesn't give a fuck.