Rainer Brockerhoff’s Solipsism Gradient blog:
People keep asking why Apple didn’t opt for the micro-USB connector. The answer is simple: that connector isn’t smart enough. It has only 5 pins: +5V, Ground, 2 digital data pins, and a sense pin, so most of the dock connector functions wouldn’t work – only charging and syncing would. Also, the pins are so small that no current plug/connector manufacturer allows the 2A needed for iPad charging.
Many people have also pointed out another advantage of Lightning – it’s reversible. Micro USB is tiny and easily damaged if you try to force it in the wrong way (I know from personal experience).
Brockerhoff also posits a plausible reason for why the Lightning to 30-pin dock connector is so expensive. Read on for details.
(Thanks to Nick Farina on Twitter for linking me to this.)