Samurai starts with lvl50 and I see lvl50 to be on par with a 1st Dan, since in my opinion Midare Setsugekka could be viewed as a typical 1st Dan Technique, regarding how often we do it even at lvl90.

so lvl50 is about practising fundamental techniques.

above lvl50 begins the Journey, Kaiten was the breathing technique to improve your performance, it gave you the task to think of Kenki to use for your advantage

Without Kaiten, playing Samurai is a stagnating experience that never really changes beyond lvl50

with Kaiten, even if they just add new skills, the Kenki Management would still be there to play with.

think of it like Overwatch for example, yes they added new Heroes but it's still Overwatch.

but Kenki Management through Kaiten was what made the Samurai in the long run.
and since 6.1 Samurai is on a boring Dead End.