Full of Misinformation, Misunderstanding and Reductionism.
Let's acknowledge these points one by one.
1. The argument that Goku's prior composure makes UI redundant fundamentally misunderstands the progression of Dragon Ball's martial arts. Ultra Instinct is not meant to be a brand new concept disconnected from Goku's past it's the divine mastery and absolute peak of everything he has been taught since he was a child. The reason Goku is the mortal closest to the angels' technique isn't because of his Saiyan biology, but precisely because of his Earthling teachings, his martial arts masters were his bridge to the gods. The manga explicitly validates this during the Tournament of Power. When Master Roshi dodges Jiren's attacks using a pseudo UI state, Whis says that Roshi's evasion is based on the same principles as Ultra Instinct. Goku's ability to remain calm isn't a plot hole undermining UI's uniqueness it's the narrative proof that the principles of Earth's martial arts are the mortal stepping stones to the realm of the Gods. UI simply takes the emotional regulation he learned on Earth and pushes it to absolute mastery.
2. The argument that Merus's death lacks the "emotional weight" to trigger Goku's transformation ignores Goku's defining character trait his boundless indiscriminate empathy. This is the same character who goes out of his way to save a mouse, who spares his worst enemies, and who genuinely connects with anyone who shares a pure love for martial arts and protecting others. Measuring his grief over Merus against his grief over Krillin entirely misses the point.
3. This also misunderstands why Merus's sacrifice triggered Ultra Instinct. When Krillin died on Namek, the sheer trauma triggered blinding rage, which awakened the Super Saiyan. But Merus's death was different. Merus was an Angel who willingly erased his own existence because he grew to love the universe and believed Goku was the one to save it. Merus's death wasn't a trigger for rage like Ssj it was a trigger for ultimate resolve. To achieve Perfected Ultra Instinct, Goku had to experience that profound loss, feel the emotional impact of it, and actively choose to suppress his anger. He achieved absolute tranquility not by avoiding trauma, but by conquering his emotional reaction to it in real time to honor Merus's final lesson. That is the ultimate test of the "calm heart" and his interaction against Moro (resisting the malicious desire to kill Moro out of revenge) was the ultimate test of the "calm mind" because he did not allow malicious intent to effect his thoughts.
4. The claim that Goku used Ultra Instinct "on command" during the Tournament of Power is misleading, During the Galactic Patrol Prisoner arc, Merus specifically asks Goku if he was backed into a life or death corner the first time he achieved UI. Merus explains the mechanics clearly to cross the threshold into Ultra Instinct a mortal requires a massive emotional shock. This shock creates a massive surge in ki, similar to the trigger for the original Super Saiyan transformation. The difference is requires the user to let that surge explode into rage, Ultra Instinct requires the user to take that immense, surging energy and perfectly control it, channeling it into absolute calmness. Goku couldn't use UI at will immediately after the ToP because he didn't know how to consciously replicate that emotional shock and suppression effect. He only learned to activate it on command because of his intense training with Merus and the ultimate practical test of controlling his emotions during Merus's death. It wasn't an inconsistency it was a learning curve.
5. The claim that UI's mechanics are "arbitrary" or "unexplained" proves you simply haven't paid attention to the manga's text or the foundational rules of chi in Dragon Ball. UI is not a magical invincibility shield the progression to UI is entirely linear and consistent with Goku's past developments Mastered Super Saiyan (Cell Arc) Learning to suppress the innate aggression of the form to make it feel natural. Super Saiyan Blue is Taking an immense, explosive amount of godly ki and perfectly controlling containing it within the body. Ultra Instinct is Perfect ki control and absolute emotional control the manga explicitly explains this, Ultra Instinct is still bound by the user's physical limits UI's accuracy drops the second Goku's emotional control wavers or his stamina drains because Goku is a Saiyan who's heart gets excited in battle and he had to fix that through faith in himself in life or death situations. The manga spends entire chapters explaining that mortals are not naturally built for Angel techniques. Maintaining the silver haired UI state requires massive stamina and exacts a severe physical toll if used for too long because of the sheer amount of Ki. It literally almost blew Moro up. None of this is unexplained it is explicitly laid out in the dialogue.
6. The most annoying criticism because it shows most do not know what "emotions" even are and they think they are in reference to the mind and not the body. The idea that the Granolah arc retcons Ultra Instinct's philosophy by allowing Goku to use his emotions shows a fundamental misunderstanding of the difference between conscious thought and physiological emotion. True Ultra Instinct doesn't abandon the concept of a clear mind it redefines it to fit Saiyan biology, Emotions are primal automatic physiological responses they trigger the body's fight or flight mechanisms before the conscious mind even processes them. You are assuming that feeling an emotion automatically means your mind is clouded. Goku's breakthrough wasn't about letting his thoughts run wild it was about letting his heart run wild while keeping his mind clear, by looking back at Bardock, Goku realized that Saiyans are naturally driven by enjoying life or death battle. Suppressing that physiological drive to mimic the natural detachment of an Angel was actively holding him back.. Instead, Goku uses his decades of martial arts training to tame the effect of those emotions. He embraces the adrenaline, the pride, and the survival instinct, etc. using them to fuel his body's raw power but he prevents those feelings from bubbling up into conscious thoughts that would slow down his reaction time. He is essentially harnessing the raw, automatic power of the body's fight or flight reflex without letting it demand control from his conscious mind. Whis's advice to "find his own style" wasn't a retcon it was the inevitable realization that Goku cannot wield a divine technique using Angelic biology. True UI is the perfect synthesis the emptiness of the Gods powered by the raw emotion of a Saiyan.
UI is amazing and you have to severely misunderstand it to think otherwise.