But what is the purpose of an MRAP (for one example)?

In the incredibly rare event you have an active terrorist attack and can move the MRAP to it before it's over, it may provide the benefit of movable cover.

The rest of the time you have to park it (in two parking spaces likely), train people with it, fuel it, clean it, maintain it. It's just a huge distraction that sends a terrible message to the people you are supposedly serving.

I'm a person that it serves and don't see it sending a bad message. They can use it in inclement weather to deliver supplies, such as after hurricanes. They also tend to deploy the armor at events that are high risk prior to an attack.

An MRAP is not going to be any better at delivering supplies than a few 4x4 trucks. They're not built for cargo and they're very heavy.

And what events in the US are at high risk of attack by IEDs and mines?

They have better ground clearance and should still be operational after say a tornado or hurricane.

A truck with high ground clearance costs more than an order of magnitude less than an MRAP to maintain.

Do you have the numbers for that?

Also, a regular truck will not stand up to storm debris in strong winds.

it allows LEOs and medical personnel to approach an area that is in danger of lethal force by criminals.