They keep the top tube prestine, the same reasoning that applies to putting a plastic cover over a newly purchased couch. Except trendier. One might question the purpose of keeping the top tube prestine by covering with a pad if the top tube is never seen due to it being covered by a pad. A conundrum to be sure. I imagine that groups of fixed-gear fanatics get together in covered garages under low UV light and gently remove the top tube pads and admire that beauty that is their top tube for a brief moment before the light begins to break down the paint (30 second window, I think). At which point the pad is quickly restored.