... and equipped with tiny little pipe-cleaner arms? ;^)
(I know, some folks once they've gone "tiny" are just never able to go back. But I'd say for most people the difference between lugging around a four pound something and a six pound something just isn't that huge a deal.)
Two words: screen resolution. That's my excuse for preferring the 14-15" size, anyway. The 1024x768 of the 12" Powerbook is *so* year 2000. (And honestly, with the slow pixel bloat of modern GUIs the 1280x800-ish widescreen resolutions of five-year old 15" and current 13" or under machines still seems awfully tight when your work style involves having multiple terminal windows and a documentation reference visible simultaneously. One of my favorite screen size/resolution tradeoffs is the 14" 1400x1050 in a five-pound-ish laptop, which unfortunately is a combination that's going extinct in the name of widescreen everything.)