Master cylinder reinforcing plate

When I was at Carlisle this year, I took a bunch of under hood shots, and noticed that some cars had reinforcing plates for the master cylinder and some did not. Is there any particular reason for this? Some were manual brakes, some power. The reason I'm asking is that there is some pitting on the firewall around the master cylinder, and I was thinking of getting a reinforcing plate to hide it. My car didn't have one on it. The guy that painted my car didn't spend the time to fill in the pits before he shot it, and I'm a bit anal. Anyway, does anyone see a reason why I can't add a plate? I'll be using an aluminum master cylinder, manual brakes. Thanks guys!