I have a unique line of work that requires me to run multiple large virtual machines for multi-OS development. Not all at the same time, but they must always be with me. That means at least 500GB 7200rpm drive, plus a 256GB SSD. Ideally both should be much larger.
At the same time, I don't want an all-in-one, because I already have nice monitors, and I need a single computer that I can carry to work every day in a backpack. That leaves me with MacBook Pro (classic) or MacMini. They both allow me to run a dual-drive configuration. I know I'm the minority, a niche customer, but I'm sure I'm not the only one who needs larger storage than the amount of SSD we can afford/justify buying. And those standard 5400rpm drives come out of my machines the day after I buy them.
I really hope that the discrete GPU option still remains available. It should even be introduced into the Mac Mini as well. The Mini is a very nice portable desktop for those who want to carry a computer, but don't need a built-in display and keyboard. I have a hard time working on a 15" laptop screen, retina or not, I'm so used to 27".
Technically I don't need a gaming PC, but if I spend that much, why would I settle for something without a dedicated GPU? Especially when we can use the GPU for things other than gaming.