i got a 12-inch macbook retina last spring, figured i'd weigh in on the usb charger thing. i hated it at first, but i'm pretty ok with it now. i'm already pretty cautious around my computers and wires and such, so tripping on the cord isn't a big issue for me; but, i do enjoy that 1) i can charge my laptop and phone with the same small charger, and 2) that i can finally charge my laptop with my portable battery. that's clutch for me.
it's a half-dozen-in-the-other kind of thing for me.