Maybe I'm afraid of change or something but I really like using Poser and since I only use it to make images for fun (just for my personal collection and some friends who like them) I just don't have a need for using any other programs.
 
I guess its similar to how I actually do have Photoshop but continue to use PaintShop Pro because its something I know and am comfortable with. And for 3d modeling, I still design and build in Spazz3D then export VRML to import to Flux (which of course I could model in there but don't know the program so don't use it) then to export again as 3ds. 

I think its all a matter of preference. If you plan on making your artwork a business or would like it shown worldwide then it would be a good idea to use the other/better programs. But if (like me) you just do it for the fun of making something, then stick with what you know "If it ain't broke, don't fix it" right?