The purpose of a wheel cover
at least where I live, is to keep your hands from freezing on the wheel - they do get cold. In some areas I'd bet they get too hot to handle.
Unless the cover is absolutely horrible visually, if it functions for these reasons, why not just leave it?
If you do put leather over it, be careful, because the width of the leather covers is based on the circumference of the wheel SS tubing. If the existing rubber is thick, the leather won't fit over it. Usually the leather kits are pre-drilled for the thread. It's still a hand-numbing experience sewing one of those leather covers on. My fingers still hurt from doing it nine years ago!