The Humvee was not designed as an Armored Personal Carrier.
It was designed to replace the Jeep. To carry more equipment than the Jeep. To be Enclosed, unlike the Jeep which was open.
Yes there were some items made to protect the soldiers inside the Humvee. But it was not designed to take a hit from an RPG nor a mine.
Those are the jobs of the Strikers or APC.
I am sure a Freeper can explain in more detail than I can. As I am only a layperson.
The phrase you're looking for is "Battlefield taxi." You are correct, the humvee was not designed to be a battlefield taxi. It was designed for maximum maneuverability and the ability to follow the armor.
The Bradley is a decent battlefield taxi, although it is frequently used as a light tank. The M113 is a lousy battlefield taxi, IMHO. The Stryker is worse.
The biggest problem is that our long-term logistics planners are still clinging to the idea of a linear battlefield in which there are "safe" rear areas for light-skinned vehicles to operate. There is no such thing. We need to up-armor the Humvees as a stopgap measure, but the real answer is that we need an *armored* cargo hauling vehicle.