This suggestion is not new. Unfortunately FD gave it a hard no many years ago. The simple reason: consoles and the button limits on their controllers.
As long as we don't have crossplay, i personally also don't see how the option to have more fire buttons would be an unfair advantage to us PC players, but that's how FD wants to do it.
What i personally would value even more would be more flexible utility slot buttons. We currently have dedicated buttons for heat sink, chaff, SCBs and something else... what was it... uh... ECM i think. Whatever that is again, has anybody slotted one of those in the last 5 years?
At the same time, some other things need to be put on fire groups. Most prominently in my eyes, the shutdown field neutraliser. What i'd really like to see would be, if the currently existing bindings for those specific tools would rather be changed to be "Utility A/B/C/D" and you could put different things on different buttons, the same way you can put weapons on the two fire buttons.
A lot of flexibility gained, just by extending the existing system to also include a few utilities.