It can negate the need for a roof at high speeds, which has saved me on many road trips

(but be careful about driving fast in the rain)

Much more significant to me is the clear vision it affords when you come up behind a large truck/semi in wet weather. Makes passing at least possible, as opposed to being stuck, unable to pass, in a cloud of dirty water for long stretches of time.

i wonder how high pressure air nozzles would fare in this application. have a small reservoir of water dispersant that get nebulised from the nozzle themselves every box and then and just push water around with the nozzles at low speed