Was the mole in question diagnosed as "clinically benign"? I can understand being concerned about a decision NOT to biopsy an atypical/dysplastic mole.
Also not sure why the removal site cannot be monitored as well. Are you saying it's easier to detect cancer if the mole is in place? If so, how should that benefit be balanced against the likelihood of eliminating the cancer via removal? Seems like most patients would prefer to have a mole removed rather than leave it in place so they can monitor it.