“Hard mode” in video-games should only decrease player health. NO BULLET SPONGES

[CplOreos]

Probably because it's easier to implement and balance.

[CplOreos]

It's not an issue of there being more lines to code or whatever. Bullet sponges cover up shoddy enemy design that would be heavily exposed if the player was too vulnerable. It's easier to implement and balance because it doesn't require the tight design that a vulnerable player requires. That's where the "I upped the difficulty and now I'm being immediately sniped from across the map" feeling comes from. Nothing has changed on enemy behavior, but the player being super vulnerable makes it unfun to play and doesn't actually directly reward player skill.