No.
1. It is a moral statement, at least in that context (while you can make that case in others)
2. There is no "earlier point" here where Luffy was unfocused and entranced by his own power. The naivity of Paradise is not present anymore, what you are seeing, is a lack of focus and a surplus of ego. Which is the reason why Gaban made a point out of it. Luffy got cocky through freedom and power as anyone would.
This is not a regression, it's the addition of a new flaw something created at the intersection of his power rise and new title.
Yes. That is precisely why it is good.
You are supposed to notice that. You are supposed to question that. You are supposed to understand that it is the reason why Luffy got defeated here.
As I said it is the addition of a flaw. But that is semantic. The important thing is : this is good characterization.
It makes Luffy a more complex character (which he already was btw) and someone that can still learn. The point of Marineford and Whole Cake was never to set Luffy's maturity in stone, it was meant to give him the tools to do better next time.
I think some people don't like unserious and edgy characters.
Luffy is exactly who he should be, he has in fact never been so much "Luffy" than in Elbaph. What we need is not more stoicism, it is more focus and less ego.
You are already all saying the same freaking thing. We get it now. You don't like cartoons and you like your men edgy and full of aura and muscle.
What I'm asking is to let the room for more positivity to strive. Our time needs positivy, not edgelords.