well, older laptops had top mounted hinges that allowed for a lot of I/O real estate on the back. that allowed them to work well on a tight desk, with power, usb hub, whatever coming out the back. for a portable machine, i think most accessible things should be on the sides, and the newer hinges on most laptops that are mounted to the back of the chassis mean that back mounted ports aren't an option. the obvious function first choice is side mounted ports, with a bottom dock with power redundancy and everything else. best of both worlds. i don't know if older laptops are the relevant comparison point to a new imac all in one desktop though. I understand why they are on the back, but its clearly not a function first decision (putting them on the front would be way more functional.