By the way, I always wondered why those restrictor rings can't be moved more smoothly.
I think the answer to that is a result of the industry we are building from. Back in the day it was good to have joysticks configurable so they apply to more game types but they were expected to be used in one configuration in the cabinet
I think you have a point there. Even in today's retro gaming community, cabinets that are dedicated to specific controls are not uncommon.
I wouldn't be surprised (or mind that much) if someone started producing new plates based on the above modification. I briefly thought about it but decided that the other overhead items that I would need to put in place first over rode any profit I might make on such a small item.
Also, the existing plates are most likely patented, so you would have have to design a new plate from scratch, get permission from the patent holders, or risk being sued.