Yoshi-P addressed this while reading patch notes and said they wanted to change up both Samurai and Ninja. They are closely monitoring feedback and may make further changes (or reversions) in 6.2 depending in community feedback.

He also said they were going to make a separate post about their reasoning for the changes, which I'm highly interested in seeing because they really feel out of nowhere, especially when there were several other routes to reducing button bloat than removing Kaiten. He's apparently aware a LOT of people aren't happy.