The Pardon is a structural check on the legislative and judiciary. It cannot be done away with safely without causing massive problems down the road. If anything, this should be a learning experience for the country not to put criminally inclined presidents in office.
The pardon has been abused by almost every president in recent history to pardon their family or associates (as far as I’m aware, Obama is the only one who didn’t, but please correct me if I’m wrong).