I have a roof rack on which I put piping insulation over the bars and place my kayaks hull-side up. I then secure them with straps to the bars and ropes to the bow and stern. Why do people spend money on attachments to place their boats on their racks hull-side down? I see the benefit of J and vertical racks if you need space but with 86" crossbars, I don't need it. What is the benefit? What am I missing? Why should I spend the money?