i use them, coz no matter how good the booty waffle, a shiney smooth top sheet is always gonna be slip slidy.
it might not look tres chic, but it would a be a damned shame to strain a groin and inhibit a day or two's sliding, just coz you did the splits when getting off a chair lift!
having said that, i resent forking out top dollar for such things and the ones you buy are stoopid large and so i get a bargain basement foam rubber one (usually simple matt black) and cut it down to about egg cup diameter size. its all you need.
Just coz you don't understand it
Doesn't mean it makes no sense!