I had cooled seats in a couple of Ford's I've owned. Hell, Lincoln even has a massage function in their newer cars. I wish Jeep would consider vented or cooled seats since i'm guessing a large percentage of their owners do take the tops and doors off and that black leather gets pretty darn hot!
I bet water would destroy the system quickly and that is why its not offered in the wrangle line up. Our on grand cherokee had a window left open during a rain storm, and it took a long time for the heated seat to work properly and I was thinking it would be done for good...but it still works.