All the pro tournaments in Japan have a collared shirt and slacks requirment and I think all filmed matches require a dress shirt and tie. They usually wear bow ties because normal ties tend to get in the way while you are playing. The vest is so that they have a place to stick on their endorsement patches, but I believe it is not a requirement (although it looks a lot better than just a dress shirt).
I think the dress code is a good thing and in Japan I think it people would follow it regardless of whether or not it was required because it looks a lot cooler than just a polo shirt and khakis.