I use a Wacom Art Pen and the reason is I love controlling the rotation of the brush. Using tilt to do this is awkward for me. In traditional oils, I use a flat brush and I can control the taper of the stroke by twisting the brush on the canvas. Like a calligraphy pen nib that is thin in one direction but fat in the direction perpendicular to the thin angle. But I like to rotate the stylus.

On some of the default brushes, one can set the "aspect," and then have a visual of the brush (either an oval or a rectangle), allowing me to see the angled aspect of the brush before I start the brushstroke and during the brushstroke.

And the palette knife has a line through the center of the circle so I can see the same aspect angle.

When using the brush creator there is nothing that I can see that gives me either of these options. I am left with a circle only. So I don't know what the angel of the brush is at until I begin a brushstroke.

Am I missing something? If this capability already exists can someone let me know where to find it?