That’s why it is important to check the thickness of your brake pads at every tire rotation, or at least once a year. Ideally you’ll want to replace your brake pads before they get to this point where the metal baking plate contacts the brake rotor, because it can quickly wear grooves in it. What could have been a close call, may now result in a fender bender instead. But you need to keep an eye on them, because while wear won't cause a catastrophic failure, it can increase stopping times. In doing so, they save much more expensive parts from needing to be replaced. There's simply no avoiding it, mainly because they're designed to wear with use.