>>105914393
At least that's what I hear from everyone. You need it because skin easily sticks to glass, adding a ton of friction to your arm which feels terrible. I've never used a glass mousepad but I've touched glass tables before so I can believe it.
Apparently there are "friction" glass pads with textured surfaces which probably stick a little bit less, but not only does that kind of work against the main purpose of glass pads, but from what I've seen people say it still doesn't reduce the skin friction enough to actually be usable.