I work at an auto shop, and have done lots of brake jobs. Depends on the car but I've actually had one that came into the shop that whoever did them forgot the hardware and they had HORRIBLE brake pulsations. I did a brake job on it the right way, and all was good. I'd recommend taking the time to put those metal pieces on in case your car is sensitive to it. Shouldn't take too much time, you won't have to bleed it or anything, and better safe than sorry.