Because the phone manufacturers who use standard usb connectors are having so much trouble...
Do micro-USB cables stream audio and video? (Remember, Lightning does essentially what HDMI does, also.) Can they be used to transmit device control instructions? (Remember, Lightning handles "dock" functionality, too.) Does the micro-USB spec provide for 2.1A (10W @ 5V) charging? (Remember, Lightning is the new standard mobile Apple connector, for 10" iPads as well as phones and iPods.) Etc.
You mean like a micro-USB MHL port that supports the USB charging spec? That my past three phones have had?
Though you'll only get 900mA@5V with data transfer or MHL active, unless you have MHL 3.0 (which is unikely at this point).
(Okay, not a microusb cable, but it can use the same physical port, provides charging and remote instructions, and adapters start at about $5)
As a bonus it will probably actually work directly with your TV if you dig the cable thing.