Perhaps a stupid question but, is it so difficult to make a Poser version ?

The work involved for building and a set of materials, yes. Keep in mind you're doing the work twice, and maybe getting less than 1/5 the return.

It really shouldn't be a big deal to at LEAST fix the OBJs so they load up in the right place WITH the textures loaded on. If making a proper Poser version is so hard, this shouldn't be a big inconvenience.