Wimbledon is a tennis tournament that prides itself with keeping old traditions. While other tournaments have adapted to the times and allowed players freedom in some sense, they have a dress code (all whites) that is unlike most is not all of the other tournaments.
Wearing headphones at Wimbledon should not be allowed, because it has its own traditions. Other tournaments and Grand Slams can decide for themselves. Just like you cant play in a black shirt in Wimbledon, no headphones or other technology should be allowed.
Yes I get it. Athletes use it. It helps them. But consider this. Maybe the strongest ones are those who do not use it, and are able to adjust to only being able to use it until they leave the change room.
There was a similar incident with a top 100 player wearing Google glass in Wimbledon 2013. Bethanie Mattek-Sands was chastised for doing so. Why choose to do this at Wimbledon if you know that the tradition is so strict?