I completely agree with you and have been very frustrated with this feature.  The date should change once you select "use" and make the necessary changes, like the amount.   

It is completely useless and such and integral part of Quickbooks.  I have called and when you talk to support about this feature not working as it should they are clearly scripted to put you on hold forever and talk to a manager that advises them eventually to say it working as designed.

I have resorted to changing to scheduled transactions and the sending me an email through workflow that it has been created as a reminder work around that the transaction needs modification.   But this is very flawed as well.