All jokes aside it's pretty wack that Orochi gets taken out just like that. There's no justice for the people of wano, the countless sumurai who gave up their lives defending their country, the 8 remaining retainers (9 if we're counting Izo) or the children of Oden who both went through shit. There is no satisfactory conclusion for them by having Orochi die right now.
On the other hand, it shows that Kaido is a savage.
It boosts his portrayal significantly and cements him as the major villain. It also shows that's he's not just a puppet Oars 2.0. You're reminded that he's a massive threat, which he has been lacking for the whole arc bar him one shoting luffy once