mapping human brain waves and utilizing it in avatars doesnt mean we can make advanced AI. it's like in the 1800s, when people say when we've mapped the entire world, we could utilize its resources 100%. now that we have, we realize that we still couldnt utilize its resources. there are still millions of places to hide. heck, alqaeda still around in afghanistan!

and u missed one, most important point in advancing technologies:

profit and capitalism.

we now have the most advanced portable technology known to man available: the smartphones (iphone, blackberry etc). do u own one? do everybody in this world own one? see where i'm going with this? economy doesnt change. the future world is still governed by economy. it's the whole motivation of humans on pandora.

and by the way, the avatars werent spies. if they were, they are the lousies spies around. why? because they have 5 fingers while navis have 4.

they are there to make contact.

actually, grace have 5 fingers too.

this was deliberate, as describe by james cameron himself. all avatars have 5 fingers, while all original na'vis have 4.