Don't discount conversions as mistreating cabinets. Conversions were designed generally to have the minimum impact on the cabinet as possible and keep the machine relevant with a new game that people would still play. It was, in essence, designed to keep cabinets out of the dumpster and remain in the circuit. The kits were built to keep the wiring, monitor, often the controls and usually PRESERVED the art.
I have, in my past, mamed a good arcade cabinet for my own use because at the time it is what I wanted. I was broke and new to the hobby and it was the only solution I thought I needed, but even then I had the sense and decency to not butcher the cabinet. I built an entirely new control panel and tucked the original inside the cabinet. Rather than damaging the wiring, I built a JAMMA insert so I could just plug and play into everything original, and didn't make a single splice.
A couple years later my passion grew with the hobby, and I revisited that cabinet. It was no effort to completely revert it back, and I am thankful. Turns out, that cabinet ended up being the 40th cabinet of the entire line built. I didn't realize that until I dug in and researched the serial number, and I am thankful I kept it all together. I have a treasure, something I never saw when I was a broke college kid who wanted a cool mame cab to help build my cred at throwing a good house party.
My point is, even though you might be giving somebody a short term gain by getting a cabinet to play with, you don't know what that cabinet will live through 10-15 years from now. Maybe somebody who played on a super cobra as a kid will have the opportunity to not only get some of their fondest memories brought back to life, but share it with people around him. That door is now shut.