If or when a Morph Brush gets implemented and we have a way to keyframe morph dials, I would like to request the ability to drive those morphs by rotating a bone joint.  Although hardly anyone seems to be aware of it, this feature has been in Poser for many years now (JCM), it's also used in Blender (Drivers), Max (Reactions I think sw00000p said they're called), and Maya (as seen here) all with different naming.

But basically the principle is the same, it's basically morphs driven by joints.
This demo by Joe Alter demonstrates the power of this simple but powerful technology :


https://www.youtube.com/watch?v=yuiB1Rv75O8