Steve Cooper has said (in a thread at RDNA) that SM did have some advance notice about Genesis. But they conscously decided not to change Poser to the extent required to accommodate what he called a proprietary system that leads off in directions that SM is not willing to go. Reading between the lines, they decided not to tie their fortunes to a system they aren't 100% confident in and which they have no control over.

I may be wrong, but I presume SM's implemenation of weight-mapping could not have existed alongside the Genesis system in Poser. And we would not have V4-WM now.