I do think its a balancing problem, but one to be solved. I originally added armor piercing to try to fix another issue actually; shotgun like guns with a lot of projectiles would be way too good vs larger enemies and most could be killed instantly just by so many projectiles hitting them and just by making them weaker would then require you to shoot weaker enemies several times instead, which feels awful. Generally large enemies will have more armor and guns with a lot of projectiles less piercing. I think you can still kill a spawner for example in one shot with a basic super shotgun if you get right next to it though.
Anyway I've planned to add more different resistances and such, right now all enemies take the same amount of damage from explosives, ice, and fire. Guess I'll have to find out if it becomes a complete balancing nightmare, but I believe its manageable.
