I know that you didn't ask me, but these are my thoughts on it. I disagree with the idea for a couple of reasons: 1) We as spectators want to see and hear the coaching happen. It's fun and interesting to see the coaches walk to court and hear what they say to their players in the intervals. And if they shout something between the point, we want to hear it! It wouldn't be the same for us if they could just speak silently in a microphone. 2) Current rule says coaching is only allowed between points. If they place with an earpiece this rule can no longer be implemented. We would have to change the rules and allow coaching at all times, even during rally.