So I would like to suggest five different features that would help artists create HD skins much more efficiently:

Layers( including layer modes, settings, and folders if possible)
Stabilizer Option
Pressure Sensitivity Support
Selection of areas
Brush Anti Aliasing Option

All of these would allow artists like myself to create HD skins on a model far easier.

These next features would be better for all users of the skin editor:

Be able to lock and unlock the camera and object movement
More useful zoom (zoom in farther and move along around the 3D space more)
Right-click to pick the color

I hope that you consider adding these in the future.