Why does the U.S. Military still use the Humvee?

[It's later than you think]

The HMMWV is completely defenseless against road-side bombs and even small arms fire can be a danger to them. Armoring them and putting a turret on them only puts strain on the chassis and makes them less mobile off road. These things are getting destroyed on a routine basis in Iraq and Afghanistan.

But yet we still use them, why?