Existing Record Rules change to default data field when a data field is deleted from an Object

Pain Point: When a field is deleted from an object, if the deleted field was used in a Record Rule, the field in the record rule automatically changes to a random field resulting in undesirable consequences.

I haven't tested what happens with record rules in tasks, I imagine it would be the same. It would be great if the deletion of a data field would result in the removal of all rules that used the data field.