Yes, Red Roc had very impressive portrayal, I don't deny that.
- Luffy is the MC and Zoro's captain.
- Oda isn't going to focus as much on reactions to Zoro's attack as he did Luffy.
- Killer reacting is sufficient for the Supernova.
- We have both Yonkou's reactions.
This makes zero sense. She told Kaido to dodge Hiryuu Kaen. It's not plausible that she thinks Zoro still couldn't harm Kaido after Hiryuu Kaen.
- Nah, we see her shocked during Kong Gatling. So Oda is clearly willing to show her reactions when Luffy does a lot of damage.
- She already knew Zoro could hurt Kaido after Hiryuu Kaen.
- Zoro's Hiryuu Kaen was the impetus of that statement.
- Kaido called the other attacks: "tricks" and "vexing".
- The object of "underestimated" is left ambiguous in the Japanese, and some official translations use "him" (e.g. Spanish Viz).
Given that Kaido only acknowledged Kokujo Ou Tatsumaki as actually successful, but was merely annoyed by Killer's attack, Kokujo Ou Tatsumaki had vastly greater portrayal.
Making Kaido cough up blood for 3 panels solidifies the magnitude of the damage it dealt.