I don't think enemies dying in 1 fewer hit while subsequently having more resources and taking less damage would make the game more enjoyable.
I think having as many enemies as the game does have hurts it more than just being repetitive, too. I'm never wondering when the next enemy is going to appear because I know it certainly won't be very long between encounters. I treat every room as a potential ambush, I never get complacent or overconfident that I've gone awhile without seeing an enemy and take a hit to my resources as a result. The mannequin in this game is fucking awesome,