The problem is that they still have a pretty small product design department, and they're committed to not shipping "crap" products.

What I really don't understand is why they didn't foresee this, and just updated their cheese grater Macs. After all, it's way easier to simply update a motherboard to fit a faster CPU than it is to rearchitect the Garbage Can design every time there's a new CPU and GPU architecture out there.

The only thing I can think of is that they've either just downprioritized a lot to focus on $new_secret_product, or that they've developed a new Mac Pro that for some reason didn't pan out, so they needed to start over again.