I'm surprised they sell any Macs with this hardware being so old. I can see a tautological phenomenon starting here:
low mac sales = low attention (neglect) by Apple = lacklustre product = low mac sales...
I personally think it's a result of bad management. It seems they pull staff from other projects to focus on the consumer products (iPhone, iPad) then the Macs get neglected. These divisions need to progress simultaneously as an ecosystem and produce at least a speed bump each year to maintain momentum and interest.
Cook needs to manage each division as a separate entity but under a single umbrella paradigm - not juggle staff based on one or a few projects. It's as if the company can't multitask. They seem to focus on one thing at a time (i.e. iPhone then iPad, then MacBook Pro). I think too he needs to start cracking the whip and start getting things done, as Steve would instead of being overly involved with PR. It seems he has more passion for PR compared to tech. Forget ambitious projects like the Apple car unless you have your core products properly managed.
But who knows what's really going on behind closed doors. I miss the days of "but wait, I forgot, there's one more thing...".