Shinnabe has been solid this tournament. What I like about her is she is so elegant in her passing. Almost always puts it right where the setter can do the most with it. I often mention player A or player B being good at receiving/passing, but I'm really just talking about the passing part. The receiving part should go without saying. I'm not sure I understand why receiving a serve should be a problem for any one of the 10-20 women chosen as the best volleyball players in their country. Other skills, I guess.
Part of it depends on the coaching that the player had when learning the game. Russ Rose, Penn State coach, said that while players may focus on specific things for their position, all players must pass and set on his teams. This enables a well rounded player when needed.
Japanese culture is very much into practice makes perfect, so the serve receive teams take a ton of practice. Additionally, this has been a focus of the national team even in Manabe's last few years. Good passing leads to a better run offense. I want Japan using the middles to help the outsides. With good passing, that is possible, without it "everyone go towards Koga" to block.
Plus with only 3 main targets (middles only take the ball when it hits the net or is too short) in serve receives, you've got to move to get in front of the ball in a short time and then get ready to hit.