A lot of folks have lamented the fact that Apple didn’t include micro USB with the iPhone 5, that they stuck to their proprietary connector. Comparing USB to the dock connector (Lightning or 30-pin) is like comparing a chair to a sofa-bed. They have the same number of similarities as they do differences.
USB has 4 connecting pins: 1 power / ground and 2 for data. Whether this is mini USB or micro USB, they are 4 pins. The 30-pin connector uses these but that leaves another 20 or so left. So what do they do?
AllPinouts has a great wiki entry on what the pins do on the 30-pin connector. If you take a look, there are pins for Audio Line In and Out (both left and right), S-Video, Component, HDMI, accessory connection and FireWire (though defunct since 2006). You just can’t do that using a standard USB connection. Lightning Port spring cleans the above and removes the older surplus ones.
There’s been suggestions of using MHL (Mobile High-Definition Link). If that’s the answer, why do Samsung get to develop their own custom version of it that uses 11-pins? If the argument that Apple should use micro USB is to be made then the same argument should be made to Samsung and any company wanting to apply MHL.