An other reason why a Dpi working feature is a Important feature.

The textures you use on the models . Take a 2048 x 2048 Texture with 72 Dpi this is actually a rather low quality texture compared to a 600 Dpi texture. Comes to it that Poser is limited like other programs on the imported Texture size but not the Dpi . so you can get a extreme high quality texture that is allot smaller in dimensions that is still supported to be applied on your models or backgrounds.