A good racquetball swing requires a hard snapping of the wrist. Because the racquet is light and small, this wrist snap not only generates alot of speed but also increases accuracy. Wearing a glove, especially a tacky one, aids the player in holding on to the racquet while snapping the wrist. This is also why racquetball racquets have a strap - to keep the racquet from flying off if one loses one's grip. Tennis, on the other hand, requires a greater variety of grip pressures and grip "feel" for different shots - drop shots, overheads, lobs, topspins, etc. Snapping the wrist is not necessary, nor effective, with most of these tennis shots and a glove would reduce the "feel" of the shot. Also, tennis is most often played in warm temperature conditions and perspiration could easily become an issue while wearing a glove.