Th problem with is they are not tie to ANYTHING in general tha can make diferent faction into something.

I mean with other faction you have some forms tha diference it: their patron god, beliefs, the land the chararter is tie for.....

What a Ork have aside of that? nothing, I will said that if you want diferent faction to exist make it like a code or something like that, something and ork always carry with it.