I propose that it might make sense to limit the ability to forget a style to a single, one time occurance. That said, this might not even make sense given that players are already allowed a one time respec and martial art style could be done at that time. Would there be any downsides to switching through multiple styles over the course of character's life span?
I have the sense that there is a lot of FOIC around martial arts, so I will keep this as vague as possible.
I think that experienced players have a major advantage over new players when it comes to picking a martial art that compliments their play style and character development choices.
Allowing players, especially new players, to have their characters forget a style would permit them to evolve their character as they learn more about the game and combat systems.