The "vast majority" of coaches break on-court coaching rules and allowing it would help "attract new people" to tennis, says Serena Williams' coach Patrick Mouratoglou.
On-court coaching is banned in Grand Slams but is allowed in other events.
Mouratoglou admitted coaching Williams during her dramatic US Open final loss last month with Williams later docked a game for calling the umpire a "thief".
Mouratoglou says on-court coaching "adds to the drama" of the sport.
In a lengthy statement, the Frenchman also said that banning coaching "almost makes it look as if it had to be hidden, or as if it was shameful".