What makes you think that any app has some kind of obligation to 'play nice' with any other app ? All apps have prop. file formats that they dont expose to anyone else, you cant open MAX files in Maya, you cant open LW files in XSI, you cant open Blender files in Wings... So why exactly should you be able to open D|S files in poser ? What the app is supposed to do is support open file formats like FBX or pointoven or COLLADA and import/export to those so that any app that supports them can use the content. And D|S is the only poserish app that does this. Our good ol poser OTOH supports no such format and people have to actually reverse engineer the pz format and write custom plugins for the damn thing.

Real generous isnt it ?