Wow. Sorry but it's kinda clear that you don't have much knowledge about this topic. Haga timings literally determine how optimally you play the class. Besides the opener, which we have many, Hagakure leads to numerous situations where decision making is key to develop your rotation. "Should I burn Haga with only 2 sen and have Higanbana inside trick attack?" "Meikyo is coming off CD with Hagakure, should I Yukikaze first in this next cicle so I can perform a non-Yuki Meikyo, or just Midare if it's close to a phase transition?" Your entire rotation is built upon these three skills' timings and how they interact together, alongside how fast you build Sen. Removing Hagakure leaves only the LVL 60 rotation behind! You always midare, no questions asked. No complexity, no thinking required, no alignment, no nothing. Just boredom.
I see so much of this going around. If you can't figure out how to align your skills in such way that Haga will come off CD exactly when you need, that's a problem in your rotation and not the skill itself. There are plenty of ways to prevent this from happening (change your opener, move your Hinganbana usage, perform non-Yuki Meikyo or vice-versa to control your GCD pace and do Yukikaze-Higanbanas when feasible to achieve the same). Honestly all I can see here is "I don't know how to implement this skill in my rotation, therefore it's bad."
That's something I can agree with. It will significantly help people who can't be bothered to learn how to properly play their class to perform better. The irony I see here is that those "mediocre" samurais couldn't care less if Haga went away or not since they honestly couldn't care less about their performance at all.
Again, is it a bad skill because you assume most players don't get it? I don't know about you, but the first time I glanced over it I could already say that insta 60 kenki was a good trade-off. There are also tons of information available out there, you don't need to be a math wizard to realize that, just look it up and see what other people have to say about it. They will literally do all the math for you.
At the end of the day, SE simply deemed necessary to reward lazyness and bad play instead of trying to actually teach their player base how to play. Not only Samurai, but other classes entire toolkit are being severely dumbed down as the game progresses (I mean, did you check the SCH thread?), their rotations are becoming blander than ever. There's only so much you can simplify a rotation before it get's boring and repetitive.
But tbh I haven't played the new Samurai and I could actually like it, who knows. I sincerely hope that I'm wrong about it but I highly doubt it.