I got my 13" MBA last year for $900. From what I have read it's WAY more powerful than the new MacBook and also obviously cheaper. I'm not really sure what the point of the new MacBook is unless it's to test the market for going WAY thin. The ports stuff isn't much of an issue because of all the wireless options we have and the adapter cables you can buy.
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I think the point is just to make the smallest laptop possible.
Assuming you want a full-size keyboard, the width of the laptop is constrained by that. Then assume that you want a 16:9 or 16:10 display, which most people seem to. That gives you the smallest possible length of the laptop. Make it a fraction of an inch thick, and bob's your uncle, you have the smallest laptop that's theoretically possible that would be convenient for anybody to use.
It's interesting that technology has finally gotten us to the point, today, where laptops just can't get any smaller.
(Although I suppose one might argue that the 12" PowerBook got there first, although its 1.2 inch thickness and 4.6 lb weight seems kind of enormous these days. Maybe in another 10 years we will all think that 0.5 inches thick and 2 lbs is pointlessly large for a laptop.)