There was a story on here a few weeks ago [1] where retired grand master Vladimir Kramnik advocated for getting rid of castling. He worked with the Alpha Zero team to investigate the ramifications. They re-trained the network from scratch on the rule change and Kramnik claims it’ll lead to way more interesting games at the top level. It remains to be seen whether this plays out in practice, given that humans are more risk-averse (particularly in sharp positions) than Alpha Zero.

[1] https://news.ycombinator.com/item?id=21789224