Mitch, I'm not trying to argue....but give the bottom section of the Account Register a try. I counted the # of clicks and they are actually the same. You select the Vendor and enter the Description and enter the $ amount and click Details and all that is filled in the Payments & Purchases. So the only difference is that you click the Details button after you enter the Vendor and Amount as opposed to clicking the Purchases button before you start. The advantage to the bottom section is that if you're in a hurry you can save the transaction without entering the details...and your bank balance gets updated.
The reason we can't change the way the purchases box works is because this same box can be accessed from outside the Account Register. And in that case it makes sense for it to default to the first account in the Chart of Accounts.