Why can't it be more casual? Tennis is one of those few sports where you have to have a press conference after every round win or lose at these premier events. That's part of media obligation of playing an an individual sport I guess. Any other pro sport that is team based is just a scrum of media coming into the locker room post game just trying to get a few quotes. The fact that tennis players are obligated to be placed in this formal, uptight setting right after a hard fought match must be pretty annoying imo
Not to take away from the players who can present themselves better in these settings, but I don't think that should be the norm/standard just cause other people can do it well. I like that Osaka seemed more human and casual about her press conferences. In the end, these press conferences are more for the journalists and reporters to write their stories/articles. It's not like we really learn their whole game plan or some other big revelation. They're just fishing for quotes. Obviously if you have a terrible press conference or speech, it can come back to bite you and hurt your public image/marketability so there's a fine line to draw.
Obviously, her acceptance speech isn't what you wanted to have heard from a winner of a premier event. She even said herself that she practiced what she was going to say but just escaped her, so it's not like she's not putting in the effort.