The lack of instancing is because there's no need for it. Consoles in general have low-level graphics APIs that let you make tons of drawcalls without the performance issues you get on PC.
Anybody got a quick explanation for why desktop APIs have such trouble with lots of drawcalls? What is it that Mantle, Metal, etc. do differently that saves so much time?
(And how much of that is a problem with just OpenGL vs. how much does it apply to DirectX as well?)
That blog post should help you clarify the difference. I think the primary problem it that OpenGL and DirectX handle changes in pipeline state very poorly.
