Yeah, they really went for "less is more" in this case and it didn't pay off:
Prince Zuko gains the most from the show’s writing, with an expanded look at his rivalry with the human weasel Commander Zhao (Ken Leung), as well as his relationships with his uncle Iroh (Paul Sun-Hyung Lee) and his father Ozai (Daniel Dae Kim). And yet, when it comes to condensing the 20-episode “Book One” of the original series into only 8 episodes, so much is lost. Netflix’s Avatar: The Last Airbender suffers from the same issue as Disney+’s recent Percy Jackson adaptation in that the characters are too far ahead of the story, with so much of the meat of the source material getting cut that the plot developments come across as way too convenient.
I agree that making things bloated can be bad, but Avatar: The Last Airbender was great because of its filler and slice-of-life episodes; it could take a break and come back to the "serious" stuff later.