I think it comes down to several important things concerning V4 (and her kin) versus the Poser core figures.

V4 has large support via the DAZ PAs, Platinum Club team and often its a unified front.

The Victoria line has a reputation of quality and features - I'm not necessarily talking about V4, but going back to the beginning of the line.

The Poser core figures haven't fared as well.  They tend to require a lot of work to get the same feature set as the DAZ lines.  Small details are constantly missed - picky details that DAZ tries to fix in their figures.  If SM really wanted the community to be more prone to adopt their own flagship figures, I would highly recommend that they run a survey and see what users really want.

I'm not trying to side with anyone regarding this, nor hurt any feelings.

I agree with Sean and others that feel that the V4 mesh is too poly heavy.  I also personally don't like the embedded deformers in any of the figures.  It feels kludgy to me.  M4 proved that you really don't need it.

I don't really care for the empty channel injection system either.  Rather see PMD adopted for figures in Poser and let DS have it's own binary system.

So, I have gripes on both sides.  I have adjusted to the things I really don't care for and when I can, I create my own solutions - pre-inject my figures and save out PMDs, for example.

.