OK, here's the scoop about Orre. Its-A-Big-Desert Definately not a good place for Ash and friends.
There's no wild Pok?mon there. (although I was wondering why a Skarmory was flying around in the intro of Pok?mon Colloseam) Also, there are relatively few gyms there who don't even participate in the Pok?mon League... no badges! All the hero (Wes?) does is foil Team Cipher's plans, which of course isn't the main path of being a Pok?mon Master/Champion.
It's probably not a good idea to travel around that region without a vehicle. You never see the hero walking around the desert, at least not without his ultra-?ber bike!
Besides, there's also another Pok?mon game being developed for the GB besides FR and LG. Probably more trainer friendly!