A good way to put the Kaiten change (regarding mechanics, not numbers or performance) is that it brings Samurai closer to Scholar levels of pointless resource bloat.
Aetherflow and Faerie Gauge (especially faerie gauge) have no meaningful interaction with eachother (you gain faerie gauge from using aetherflow abilities wooooo).
Scholar is in sore need of a complete retooling regarding it's resources, either turning the faerie gauge into something meaningful to spend, like an addersting gauge (which is more exciting at least), or interact with it's kit.
Kaiten was the only thing that bridged the gap between the stickers and the kenki gauge. Now you can throw the kenki gauge off screen because you don't need it any time except for dumping on a button that glows.
If shinten glows you press it, if shoha glows you press it. (pooling has also been diminished since the trick attack change got rid of our 1m window where we DIDN'T have Ikishoten)
They said they wanted to make way for changes in the future with kaiten's removal, but should have honestly held off until they had something to REPLACE kaiten. It's quite literally a faerie gauge now.
Oh and if anyone is excited because it frees up button bloat there are nearly half a dozen better solutions with no downside whatsoever in every Samurai forum, please don't settle for less.
They could have gotten rid of TWO buttons instead of one this patch but didn't.
Imagine Ikishoten gives you another buff like Ogi Namikiri Ready, called lets say, "Hissatu: Ready" and what it does is change Hissatu: Shinten / Kyuten into Hissatu: Senei / Guren respectively, and when you press either ability the buff gets consumed.
You still have Senei and Guren in the game, they're just bound to Shinten and Kyuten respectively, functioning 100% the same, and ALSO IT REDUCES POTENTIAL DRIFT since the CD is tied to Ikishoten, lowering the skill floor for all sorts of players.
And thats just one idea that has no drawbacks whatsoever.