Why much of the pieces of evidence for primate evaluation analyzed by anthropologists comes from teeth along with jaws?

I suppose because you can tell how strong the jaw muscles are from the connection points, and you can tell what type of food they're eating from the shape of the teeth. Looking at evolving animals in the same group you can tell if their diet had changed over time.

The enamel covering a tooth is already 97 percent mineral, and teeth are stronger than bones, so they’re more likely to survive.

Fossils are hard to come by and you work with what you can find. Ideally, there should be complete or nearly complete skeletons and perhaps even soft body parts preserved.  But if a few teeth is all you can find, then that is what you have to work with. 

Linda and me have the cute jaw thing.