Quote - I wonder what the real motivation behind this move is.

Why should it be any more complex than trying to kick-start the demand for Genesis-compatible products outside their own relatively small circle? Maybe there was a push from the Daz vendors for the company to do something to expand the Genesis base. V4 / M4 products pulled in buyers from all over the hobby. Since the change of focus to Genesis, the market shrunk to those using DS4.

Genesis requires DS4, therefore they need more copies of DS4 out there. Seems fairly straightforward to me.