Better armor on the vehicle doesn't necessarily ensure that the riders inside the Humvee will live, either. The first time my husband was in Iraq, there was an incident in which a very large explosion completely demolished an up-armored Humvee. The only person who lived was the gunner, and that's because he was blown from the vehicle. He wasn't in very good condition following the incident, though.
I dont understand why folks are suprised, this happens every war.