I think that this would be a REALLY handy feature. Often times I need nice-looking screenshots (no overlays) out of the development environment during submittals and find myself changing value sources often.
I could do this manually, using a single-tag UDT with 3 parameters (type, value, path) that I can just change the value source on, but it would be nice to have this functionality natively. Using the UDT I would have to expand every tag down at least one level to see the value in the tag browser. Not ideal.