Your instructor likely flies mostly in other people's airplanes, so what does he care about a tarp abrading the paint off when it flaps around in the wind. Bruce's covers are made from a material that is tough and UV protected on the outside and soft against the paint on the inside. The stitching, corners, straps, and grommet pockets are sewn to also not cause damage. Their covers last for years.
I don't know where you're based, because you haven't yet filled out your profile (please do, so we can get to know you!), but if you're somewhere it rains or snows you'll want the over the top canopy cover to keep water from intruding.
