From the Q&A at WSJD Live, November 2014. Starts at 28:45 in the video.
Q: [Why did you kill the iPod Classic 160GB?]
Tim Cook: “Because we couldn’t get the parts anymore. Not even anywhere, they’re not made anymore. And so we had the choice of either of doing a total redesign, a totally new project. Or try to get people to go to the iPod touch, if they wanted a sort of dedicated music device. iPod touch is not really a dedicated music device, but I think you know what I’m saying. We’re shipping a lot of flash in it now. You can get almost all the ones that you get on your Classic. Not quite yet. Over time, that might change. And so, it wasn’t a matter of where I was swinging the axe saying, let me see what I can kill today.
The engineering work to design a whole new product was pretty massive. And the number of people who wanted it, very small. Sometimes we decide to do those anyway, like Mac Pro. We’re doing those for our creative customers, but in the case of iPod [Classic] I felt that there are reasonable alternatives there and I’m sorry if you didn’t feel that way, because I want to keep you as a customer. But that was the rationale.”
To put it in other words: The Mac Pro wasn’t making enough money to justify the 2013 redesign in the first place from a pure business perspective. But they did it anyway for their creative customers. Is the MacBook Pro 2016 a reasonable enough alternative?