SAP did not design this application. It was acquired through acquisition. As such it is not completely in line with other SAP applications. The change history is one area where it is less robust than other applications. Another area is the object transports. Sourcing does have its own version of this but it isn't nearly as complete and robust as other SAP products. There are not currently any plans that I know of to change the change history. You could certainly state your concerns in the form of an enhancement request.
Regards,
Gary