Removing helmets and armor is welcomed. Enemies that don't react to being shot piss me off, and is common throughout the genre. "Armored" human enemies that simply require X amount of bullets to provide a simple reaction (typically just DEATH in Conduit1, otherwise they strafe and move like a everything's fine) is a stupid design choice, basically shooting at arrogant cardboard until they fall.
If the removal of armor indicates a signifcant change to the enemy's vulnerability, creating an opening for a definite kill, then that provides a much better impression than the last game's cardboard. There should be increased variety in reactions, period, including reactions to explosions. RE4 is full of reactions, so each shot to different parts of the body generates satisfaction.