If you know that a gesture is expected, the hand is not necessary. However, it's unlikely that people would recognise they are expected to gesture without some

If you know that a gesture is expected, the hand is not necessary. However, it's unlikely that people would recognise they are expected to gesture without some context - the clearest way to indicate the correct context is with the hand. The hand is providing a necessary function here - although I agree it might be a bit heavy and that it will be less necessary once you've established the context.