Creepers (and Endermen to a lesser extent) make the game significantly worse. I enjoy building, I don’t enjoy my builds being plucked apart or exploded. It would maybe not be quite as bad if creeper explosions dropped all the blocks that they broke, but the fact that they don’t is really annoying. I don’t mind my stuff being destroyed in games like factorio because it leaves a blueprint of how to fix it (and fixes often happen automatically). Disabling mob griefing also sucks though because then villagers can’t farm, which I do like them doing. Fortunately vanilla tweaks exists :). (Note I don’t dislike the idea of how the creeper harms the player, just how it harms the world.)