The easy answer to this bait is to ask the question "why".
Why make a entire mech when its main point was the spirit cannon
Why does Korra become a big blue energy spirit as a non Avatar, why did it have to be her, why make spiritual energy into chest energy beams.
The answer is because it was supposed to be cool, but it ends up being no more that that. It adds nothing to the series besides spectacle, and obviously that spectacle doesn't hit for some of the anon here.
The drill is needed to get through a wall simple and straight to the point, its more superlative than it need to be.
The Godzilla fish thing shows not just the Avatars connection to the spiritual world but what the ocean spirit characterization even if just a little bit. It shows the culture of the norther water tribe the reverence the waterbenders have for the ocean spirit all while being cool. Korra in my opinion unfortunately does not.