If aliens must play all the game with in-mouse view, humans must play all the game with in-barrel view. All the time.
It's only good in movie opening scene:
Not while playing (imagine playing Quake III Arena with in-barrel view).
Well they did solve the feedback problem. We still have to find a solution for dretch and goon (and fix the first person claws for all others).
Symbolic feedback is good (sound, icon…). People like to have a different gameplay while playing aliens or humans (that's also why they love this kind of game, to be able to alternate from human and alien each games), so you can use different feedback mechanism.
In fact you already have different feedback mechanism: Humans have trigger feedback (plus opponent's dead feedback, if visible), Aliens have hit feedback. The game does not feedback the same information if you are human or alien, so you don't have to display these different feedbacks the same way (and if you do, it will be weird).