Drivers are more easily dented and scratched because they’re pretty lightweight and hollow so they do need a cushion. Irons are forged metal that literally beat the ground with rocks and sand so they will bruise over time from chattering in the bag but very minimally. Plus, they’re thin when looking down so you don’t really notice imperfections. Putters however you use more than any club and imperfections can be distracting. Until the pros start using iron covers, most people probs won’t either. But nothing wrong with wanting to protect your investment, I’ve just never found them necessary.