All good points to consider. 

Overall, I think it is about quality over quantity in most regards. 

The Daz figures are higher quality than most of the others available, even if they are not as anatomically accurate as the others. The meshes are generally cleaner, uv maps easier to work with, and the morph combinations are much broader - all three aspects that most of the other available figures fail to provide. 

The one thing that has always bugged me about Daz figures is that in most cases, no matter where you are on the web, you can almost always tell if its Vicky or Mike being used. It goes beyond the joint bending issue that's always been a problem in both DS and Poser. The lack of realism I think is what stands out most. Other figures are more realistic in appearance and usually a bit more difficult to spot, but fail in the polishing, and thus fail in the vendor support. If a content artist has to contend with sloppy UV maps, or stray vertices and split seams that make morphing difficult without significant work-arounds, then the figure loses support from the vendor side. Without vendor support people aren't going to bother with it. Why spend the time to fight with the hassles of an unpolished base, when there's the Daz figures that work much better out of the box. 

There is no denying that the Daz figures are currently the best that is available. Any Poser/DS marketplace is proof of that. I just don't think it's the best that can be done by a long shot, even with Genesis in the picture. 

It also seems that most of the 3rd party figures that have come along, lose the support of their creators before they ever really get a chance to be recognized by the community. There's a lot more involved than just making the base figure and throwing it out there. Proper functionality is only part of the job and only gets it barely out the door. 

But then you have other artists who make their living producing several original figures on a regular basis, and while the artistic quality and funcionality may not be the greatest, they still manage to develop a following. If enough people like their style they can continue doing what they do.