I don't think it's the price. I think it the fault of shallow fashion. The push for the thinnest, most minimalist tablet possible, outweighs nearly everything else. If they doubled the thickness of an iPad, how much bigger battery could they fit? 4x? How much more durable would it be?
My tablet is big, clunky, but has both a micro and a full size USB port, along with the HDMI, microphone, power, and sd card, and I love it.