I do think it is a bit disrespectful to the crowd to walk on to the court with your headphones on, especially when the crowd are probably cheering the players’ names and welcoming them. in effect the players are ignoring them which is rude. However I do understand why they are doing it as it helps them stay in the optimal state and focused right up to the last minute before they have to play. At the same time they should be able to create that optimal state and set anchors that when they step on to that court its match time and they should be ready. Does that extra minute with the music on really make a big difference?
Perhaps I’m sitting on the fence a little bit here! I’m struggling to decide what I would do if it were me!