I don't mean to offend anyone with this post, and I am well aware that many mediums and shows take elements from each other, but I believe this is taking too far. I'm only here to voice out my own opinion for the series.
I've been a very old fan of the Lego Ninjago series, believe me. I liked it for about... 3 years. I'd still say, despite not being a fan anymore, that the old seasons were slightly better than what the Hageman brothers have offered us now.
What I mean by the latter is that the old seasons felt more original than the newer ones. It fit more into the theme of ninjas, samurais and the entire thing based off of Chinese and Japanese cultures.
The Skeletons and the Golden Weapons were frankly an interesting concept, I must say. The snakes? Many cultures view repitilians as a bad omen, like Christianity. Heck, even a kids show in China has a lesson about not trusting a snake.
The Stone Warriors, which I am guessing, were a nice reference to the famous places in China: the Mausoleum of The First Qin Emperor and the Terracotta Army.
If you don't know, the Terracotta Army is a collection of sculptures that represents the army of the very first emperor of China. I guess this is an allusion to the Overlord.
See, all of these previous seasons were great because it clearly made subtle references to the culture.
Now, onto Rebooted. That's where it started going down. See, implementing sci-fi and technology isn't always the best thing. See for yourself. For Fire Emblem Awakening, Intelligent Systems was about to make it a sort of futuristic area but decided to stick with Medieval Europe-inspired settings because that, at the core, is what Fire Emblem is. It's a fantasy game with places and characters based off of Medieval Europe.
For Rebooted, I felt like the Hageman brothers wanted to introduce something new. But it didn't fit the main theme of the series. They still kept elements of traditional China and Japan but it felt really off because it was such a huge clash with the futuristic setting of New Ninjago City, which is based off of modern Tokyo I believe. But Rebooted was a fun season to watch. It had a message: don't always rely on technology to solve everything.
However, it's at the tournament arc where it starts degrading. It was a total ripoff of the central idea of many battle royale series, mainly Fate. Fate/stay night and Fate/Zero, a visual novel and the latter a light novel series which both got adapted into anime by ufotable, both have one central plot. And it's the Holy Grail War. The said war is a sort of ritual where 7 Masters and 7 Servants battle each other for one goal: to get to the Grail and have their wish granted. Similar to the Tournament arc, right? Yes, definitely. Chen comes in with his staff, which is the Grail, and presents the Tournament to its contestants. The add-in with saving Zane from all of this mess is similar to the middle of the story for both Fate installments, where one particular Servant is targeted. They're literally the same. And Fate/stay night, the visual novel, came out in 2006 whereas Fate/Zero was released in 2009, followed by the anime in 2011. I can go on with the Hunger Games too, but Divergent was already a better ripoff.
Then, ghosts. Ghosts are common in Japanese folklore so I won't touch it that much. Morro's overall character was interesting because we can vividly see that he was fueled and consumed by envy towards Lloyd and Wu.
I haven't even touched a single episode for Blades of Time since I was busy with school so I am in absolute no position to judge.
Now, the 8th season. It's not dark at all. In fact, I think the creators now just want attention from a bigger fanbase and you know what's popular and successful in the west that regards Asian culture, right? Yes, I'm talking the anime named Fullmetal Alchemist: Brotherhood. Regarded as one of the best anime in time, and it's one of my favourite anime as well, I see where the brothers are coming from. They want more fans because fans like it and more fans means more money. You see, the idea of Harumi admiring Garmadon as a hero is good. It's good to see an innocent child admiring a villain of the series because we can have a different point from his actions even if it was literally just snake poison in his blood.
Reviving the said villain is also a common trait for cults, as we see in Fire Emblem Awakening again, the Grimleal cult in Plegia wants to revive the fell dragon Grima. (In which they succeeded) But the 8th season resembles so much to Fullmetal Alchemist: Brotherhood, I cannot even start with the plagiarism. Oh, the romance? Please rewrite the script. Nobody kisses someone they met for 6 episodes or so unless if you're Gasai Yuno or unless if you're thirsty. The adopted parents trope is also overused.
That being said, good bye. This is my own opinion on the show.