Quick PSA: Healing factors don't mean characters don't feel fucking pain
I don't know if Deadpool getting limbs chopped off and treating it like a minor inconvenience has permanently broken people's understanding of healing factors, but apparently this needs saying:
Healing quickly and not feeling pain are two completely different abilities.
This is mostly inspired by some of the INCREDIBLY stupid and bad faith discourse around Insomniac's Wolverine, particularly people questioning why Wolverine would bother wearing armour when he can just heal from injuries... maybe because getting shot, stabbed, burned, slashed or having chunks ripped out of you still fucking hurts?
A healing factor means your body repairs the damage. It doesn't automatically give you anaesthesia. Unless the specific version of the character is established to have reduced pain perception, they're still experiencing the injury in the first place. Wolverine being able to survive something doesn't mean he'd particularly enjoy experiencing it. Armour still prevents damage, reduces pain, keeps him functional during a fight and means his healing factor has less work to do.
Regeneration is not invulnerability, and it definitely isn't a permanent morphine drip. I genuinely don't know why this distinction seems so difficult...