Business Rules should be extended to apply to fields on a business process flow only - allowing the field to remain unchanged on the main form- but affected on the business process flow stage.

For example- I should be able to enact a business rule that would make a field mandatory on the business process flow stage (preventing the user moving to the next stage before it has a value), but not the main form (which would still allow the user to save the record without providing a value for that same field).