One of the things I hate the most about my Nexus 7 is the lack of a physical button and I also hated its lack on my Motorola phone. Plus you're often losing screen space to a virtual bezel.
The combination of a physical button and TouchID is heaven in comparison.
You are correct. However the effect is the same. I can tap my credit cards to make purchases. No swiping or PINs needed for small purchases. A phone offers me zero advantage here. Plus you don't have to configure a credit card or or worry about battery drain. Just pull out the appropriate card, of which you may have multiple, and you're done.