I feel like becoming the hokage is a better world building tool, because it forces kishimoto to have to explain technical stuff, like governments how they work and their dirty underbellies, and the economy and the effect the have on the people which is largely not good. There is a lot of poltical shade thrown in naruto. Every explanation and everywhere they go feels like they are contributing to the narrative, which to become a political leader. So Naruto going around the world and helping people and learning how the world works directly contributes to that.
But when you come back from a time skip and be like " i wanna be king of the pirates, ooooh! fish person world" My response is who gives a shit where is the godamn X
Edit: Also I heard Dude wanted to make the teenage like more anthropomorphic version of chopper the main chopper but some editors was like no we need a mascot. You wanna know who the mascot of one peice is? LUFFY. You don't need another mascot , people word associate one peice with luffy.