Why does he think his movie was a mistake?
http://www.japantimes.co.jp/culture/2016/12/27/films/please-dont-see-animated-blockbuster-says-japans-new-miyazaki-makoto-shinkai/#.WGJ9rxsrLIW
So he is really saying he wants you to see it. Shinkai was a mistake. He's nothing but a hack.
Reverse psychology.
He didn't find a way.