Just because something isn't technically a premium feature doesn't mean that having more of them wouldn't cost more though. Another example would be a car with 7 seats over 5, the seats aren't a premium item but having 7 over 5 is, hence the additional costs. If you need 7 seats (which the majority of people don't) you'll pay the additional costs to have them. I would guess for most users of the mITX platform 4 USB ports is enough, which pushes anything above 4 into the 'luxury' feature set.
Even If we just accept that it then just leads to the next problem, which is that mainboard manufacturers are horrible at offering a decent selection of ITX / mATX boards while they keep carpet bombing the market with ATX boards that are pointless due to the massive PCI-e lane restrictions present with all mainstream CPUs.
To wade in on the hub debate, I use a powered USB 3.0 hub because it actually makes my build neater. Rather than having a shedload of cables running from my keyboard, trackball, scanner, card reader, graphics tablet and so forth to my desktop - cables which will never reach anyway, because my desktop's on the floor and I have a convertible sit/stand desk - I have a shedload of cables running to the hub on the top of my desk, neatly hidden away behind the monitor, and one cable running to the desktop (plus another to a power socket, admittedly.)
I was thinking about this a bit more as the hub can be hidden. Still, I would prefer that it is my choice. Especially as I've found in the past the hubs and extension wires have cause issue of devices disconnecting. I was thinking on this a bit more, and a usb 3.1 or similar hub should be able to ditch the power cable.
