Apple has trouble seeing themselves as sellers of commodity hardware like you describe - they never did, and there's a lot of pressure to innovate since Jobs left.

Due to this, they try to innovate on form-factor, which is the aspect they have most control over the product design. The problem is that this is directly at odds with 4) price, 5) expandability and (to a certain extent) easy to 7) spec-bump every year.

So I think it's very unlikely the next MacPro will fulfill this wish-list, even if it seems rational at first.