If you can feel pain in the legs, then you miss "issues" like infections or sores or other problems. Those issues that you don't feel can then cause problems for the rest of the body ... from blood clots to infections to sepsis etc etc etc.

I knew a man in Michigan who had paralyzed legs and was considering amputation. I think the doctors and he has more or less made the decision that the next time there was an issue, that amputation was probably the best course of action.

I certainly don't know all the issues, and I'm sure that amputation has it's own set of issues .... but that is what one person told me maybe 25 years ago...