smiling or not smiling isnt the central issue here tho it contributes to it   
look at what's being said.
	
	
		
		
	
	
I had this particular issue  after this chapter  and I described it as a strength measuring contest in a friendly rivalry   cause it evolved to that. 
his fights particular when he is fighting against someone that has hurt a lot of the people  he has come to care for carries higher emotional weight which is what makes it so satisfying when the villain goes down.
different != better  
when that's reduced to both alluding to having fun esp luffy because I could care less what kaido does till he is fleshed out,
then it begins to feel like beating kaido is just to tick off who luffy aims to surpass . it's fine if luffy wants to beat  kaido to surpass him but the story has made the battle to mean more than just that. 
have fights resembled these ?  yes roger and whitebeard from the little we saw had but neither wb nor roger had reasons to bemoan the other , that's the important distinction .  that's not the relationship luffy and kaido share or have. 
oda did a great job of allowing  the strawhats  the see the desolation of wano  by the hands of kaido 
you know the guy responsible for attacking otama, the death of momo's dad  , beating the scabbards near death  and all of that was to provoke some justifiable anger and you see that very clearly here 
	
	
		
		
	
	
 
 
	
	
		
		
	
	
in anycase till subordinate fights are done and dusted , pretty early to judge the fight but less of that and more of this is infinitely more preferable. sorry some fans dont want luffy having fun with the person who ripped up some of his allies , just broke zoro in front of him 
and killed momo's dad. 
joyboy argument  is lame ; luffy didn't start being joyboy when this fight started so I cant help but laugh when people try to use that as a justification.