Maybe this is a dumb question, but I've been working on covering the butt ribs for the last couple of evenings and I'm starting to wonder -- is this trip really necessary?

Is there a functional reason for covering the butt ribs or is it just for looks? Does it keep out the wind or something? Besides being a pain in the a$$ to cover, the idea of peering though a plastic window to try to read a couple of sight gauges that are probably going to be kind of hard to read anyway, really bugs me.