Apple is rumored to be working on an updated “micro dock,” which would make room for bigger batteries, 4G radios, and other components. The reason for the switch is not for political reasons like a desire to conform to outdated micro-USB standards. Apple just wants to save space inside the iPhone 5 for more important components.
Apple had switched from the common mini SIM card to the very uncommon mini SIM card for the original iPad. They took the antenna out of the core package and placed it around the edge of the iPhone 4. This way the iPhone 4 could hit the 10 hours of battery life goal. The iPhone 4 needed a Retina display, HSPA radio, 802.11n WiFi, and bigger camera sensor. This is why they switched to a smaller SIM and moved the antenna to the outside.
When the iPhone 4 was released, iOS was not yet PC free. There was no iCloud, AirPlay, or Bluetooth 4.0. The 30-pin dock handled all syncing and data transfer including music, movies, etc.