It's absolutely not making Luffy look bad, it's just gloves that allow light to be touched. That's basically like applying water on your fist to touch Crocodile. Using haki would also allow him to touch and damage Kizaru, there is absolutely no doubt about that.
Him not using adv CoC is a L for Kizaru but I think he will need it later, defeating Kizaru with just gloves make him look bad