When do you want or need a WDH and/or brake controller?

The best reason for both those items is too reduce wear and tear on the truck.

The harder you work the suspension and brakes the sooner they wear out. This is true even if you are well within the vehicle's ratings. Sometimes those ratings indicate the use of a WD hitch.

You are basically buying better braking and handling for your TV.
Whether it is worth it is up to the individual.

Like chicken soup, it cannot hurt.