I would like it to have a bit less of the technology. It just feels like Ninjago went from “The Skulkins have tanks and motorcycles!” to “And now we’ve all got Gundams and dropships and HUGE GOLDEN WEAPONS!” in just a few seasons without any explanation for how the advancements came about. It’s in the Serpentine sets that Ninjago City first appears, and it has no explanation for why everywhere else is stuck in semi-feudal Japan. Then the Nindroids appear, and it’s back to “We’re ninja wizards with tanks and mechs, because somehow all of the dragons are gone.” The ninja had significant power on their own in previous seasons, yet they suddenly become totally dependent upon technology for their powers. Spinjitzu seems to have gone from being the deadliest power a being can have to being just one of many technologies that can achieve the same amount of destruction. It just doesn’t feel as though the heroes are as powerful once they become so reliant on technology and vehicles. Their Spinjitzu abilities begin to seem redundant, given that they have vehicles that are much more powerful and have greater firepower than the ninjas or even Sensei Wu.
That’s my reasoning, but I do understand that having it mostly fantasy would make it more challenging to craft easily likeable characters and locations, and could potentially cause the story to be even harder to understand.