Most of the time you don't need one but there are times that it will save your butt. I was nearly blown off the road in a mountain pass high wind area and I was only towing a pop up. If someone was next to me it would have been a disaster. Years later I went through the same area with 28 footer and sway control. Wind was not as high and I was not going as fast but it still was not a pleasant experience.
I know that 99% of the time I won't need it, I use it for that 1%. Same reason why I have fire insurance on my home.
