dig: There have always been 2 components to Wave's offering.
1. The client software (ESC) that allows local management of most features.
2. But the ESC also acts as the local client communication element of/with ERAS
VSC can not be considered an ERAS lite.
VSC is a capabiity/feature addition. It is, obviously, a software instantiation of a smart card using the Microsoft SC overlays. In Windows Vista and Windows 7 these overlays were written by Wave.
Like all other components VSC can be managed locally in the ESC or centrally with ERAS or Wave Cloud (for SEDs). Of course, and as you correctly state, mass deployment begs for ERAS... and that is valid for all features.