Does anyone know of any regulatory reason for the reconciliation portion explaining how to balance the account?

No regulatory requirement. It's a tool that we make available for the plethora of customers who still reconcile their checkbook by hand.

<Insert Three Amigos reference here>

::raises hand:: part of the plethora.....

I balance my mother's checkbook by hand because she is 90 years old and can't understand how anyone could not balance their checkbook, but I don't use that tool on the backside of the paper.