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. Note that this refers to individual pins; I’ve been told that several devices manage to get around this by some trick or other, but I couldn’t find any standard for doing so.
The choice to not use micro-USB seems logical. The problem is not only in the high current, but it is also lacking audio/video. The price of the lightning to the old 30-pin adapter is also explained. It is not a dumb adapter, but has logic in it.