Originally Posted by Cheetah
imo it doesn't. With a bent arm you can extend or shorten the arm. With a straight arm you can only change it into a bent arm (which is no longer straight in a lot of cases) (giving a little room for interpretation of straight arm). with a straight arm if your footwork isnt great or the ball takes an unexpected bounce that puts the ball further away from you can't make the straight arm straighter. but with bent arm you are closer to the ball and can extend if need be.
Imo, the straight arm is not really any different technically than a bent arm. I mean, what if the ball is too far away from the bent arm? Are you not allowed to straighten it because then it'd become close to a straight arm? The amount of bend in the arm doesn't define the techniques.
It's just a preference of where you'd like to contact the ball that results from having one type of forehand technique which uses pronation in the takeback. Nobody should be trying to force themselves to hit with their arm straight. The straight arm should be a result of the contact point.