Eh, I guess one could make that argument. The nylon covers are pretty tough though; I have trouble imagining Velcro harming the trackball. Of course, you gain almost no benefit anyway–velcro won’t grip that ball well. A bit of soft rubber will definitely do better at improving grip. (Some neoprene roughtop that we had lying around performed the best of all the materials I tried… I still need to try this carpet stuff everyone is talking about though, and maybe some Plasti-Kote)