Another reason for me - Colorcurvatures K4-M4 Mixer. It works with V4 too. I can do kids and teens. The last kids that came with Poser were Ben and Kate, and they are not very versatile. I use the Daz Generation 3 kids and teens, and even the Generation 2 pre-schoolers and pre-teens as well. But if you need to show the same kid growing up in a story line, the mixer script makes it much easier.

Did you know you can also use it with the Generation 3 figures also?  You can.  I am pretty sure you can use it with the Generation 2 figues also (I did tests with it when it first came out.)  All you need are figures that are built from the same base mesh.
I have a whole series of mixed figures V3/L3, SP3/L3, D3/Lu3, M3/Lu3.  It is really nifty.