What does it matter that he "Outclassed" Mr. 1? He still needed to grow within the fight itself and become stronger to win. Learning to cut steel mid fight = becoming stronger mid fight.
If Zoro could cut steel at will on Skypiea he wouldn't have struggled so heavily against Ohm in the first place. He only landed one attack on him (from what I recall) and that was the final attack.
Ashura was not overkill as Zoro would have lost that fight without it. It was an ability Zoro came up with specifically to take down stronger opponents. We have no clue if he came up with it prior to Enies Lobby, or during the fight itself. Perhaps one day we'll get a better explanation on it, but for now, we just don't know.
It matters because he was stronger than Mr1 in literally every aspect, just like I said. Remember?
He needed to grow to remove the trick which was preventing him from dealing any damage to Mr1.
He didnt grow to increase his speed, his defensive abilities, his endurance, his durability or anything.
He grew to be able to damage him. He already had all stats above Mr1.
Because Ohm had CoO while Zoro didnt. Why are you asking such obvious questions?
Did you forget Luffy, Sanji and Usopp struggling against Satori who is weaker than Ohm?
Yes, Zoro's fights end when he lands one attack. That's how Zoro's fights work, he uses swords.
It was overkill because it instantly neg diffed Kaku. Zoro fought the entire battle just fine without Asura.
Again, he used it only for the ending, it is not an ability to take down stronger opponents as he needs to be strong without it for the entire fight. He isnt using it the entire time like Luffy uses gears, I told you to take Luffy lenses off.