Orochi must have a bigger role in the story. Shogun of Wano....the term kept popping since Zou. But Orochi's role hasn't been unique enough yet. Don't get me wrong, Orochi has been a great villain (much better than Kaido so far), but was Orochi indispensable to the story?!!
Let's identify Orochi's role in the story so far:
- He killed Sukiyaki
- He invited Kaido to Wano
- He planted Kanjuro inside Scabbards
- He tormented the people of Wano
- He turned Killer into Kamazou
- He kept Wano to himself as it's Shogun
The first five roles could easily be done in the story by Kaido himself. Furthermore, if Kaido were to invade Wano 20 years ago instead, Oden's storyline would make more sense.
The main plot-hole Orochi helped to cover was Moriah. Moriah came to Wano 23 years ago and fought Kaido. Hence Kaido had to come to Wano at least 23 years ago. But Oda couldn't make Kaido and Oden co-exist for 3 years without a buffer like Orochi.
I am not sure of the purpose of Orochi anymore. As opposed to being indispensable to the story, he is being used as story tool, despite Orochi being a better villain than Kaido so far.