Even for the price, if they added it it'd probably be a better value for the consumer or a 50$ Wand and a 50$ Nav with motion than 50$ Wand 30$ Nav and 50$ wand

Because it was an after thought. Sony originally thought using two wands and/or a DS3 in one hand woudl be sufficient. However, once people questioned that as not really working for all genres or comfortable, respectively, they added the navigation controller.

@OP: because you touch yourself at night.

OT: In the KB video showing a guy playing socom, it showed him throwing a grenade in a throwing motion using the navi.

would be okay if you were sitting down but I get your point, it seems like they made all games functional with one, but alot of them would work better with two

Its possible it was using the cam to detect the movement of the left arm.

The Eye does have some motion tracking, so I guess it'd work for simple things such as thrusting. That would explain why the guys on the fighting game and the sports use the Wands instead.

Because the navi doesn't have a giant glowing ball sticking off the end of it and that giant glowing ball is what the eye tracks 1:1?  Just a guess.

The question is "Why didn't they include some form of motion".

We know it tracks the glowing ball. We was wandering why it wouldnt use a chip like sysaxis in it.

Well, as you said earlier, the eye does have some rudimentary levels of tracking, so it will have some form of motion, just not 1:1 or whatever.  Maybe they just didn't want to stick an ugly glowing ball on it?