P: Change Brush Size using Pen Tilt

Also, there's no need to make any changes to Photoshop's user interface, since the option has been there for a decade, in the Brush window:

I concur. This man speaks the truth.

This man speaks the true!

I like this idea!!

Addendum:

1. I understand that Photoshop already implements several ways of changing the brush FORM by tilting the pen ("Tilt Scale" and "Brush Projection", on "Shape Dynamics"; and "Airbrush tip", "Bristle tip", or "Erodible tip", on "Brush Tip Shape"); however, none of these features allows to JUST CHANGE THE SIZE of the brush.

2. Since version 7, Photoshop's UI (as well as its documentation) suggest that this functionality is possible by selecting "Pen tilt" in the "Size"/"Control" list, on the "Shape Dynamics" section of the "Brush" window, but, alas: that only enables the "Tilt Scale" slider, and behaves otherwise as if the "Pen Pressure" option had been selected.