I think that like everything, it all comes down to execution. Ultimately it helps to just look at everything as stories. If those stories can be translated effectively into new mediums – do it! There was definitely a time when making some stories into a movie was a technological barrier of entry that animation could always surpass. Then as technology got better, that barrier continually got smaller and smaller until it's basically nonexistent anymore. TV also had that barrier for a while, especially because of budget – and it had different constraints than film had. Film had to condense stories into a ~2 hour medium, whereas TV could tell them in multiple chunks of 20mins - 1hr at a time that was more like chapters in a book. Long-form storytelling got better, and that's why trilogies & series became more popular, and cinematic universes started happening. Then eventually fed all of that back into TV again.
With ATLA originally being written for TV, it won't have the pacing difficulties that book adaptations can have. If they can pull of the story and bring about some new goodness with the live action medium, like I said before – go for it!
Also, being that it's a Netflix original series, that also means that blind/visually impaired people will be able to watch it – since Netflix always has audio captions for all their original content. Anytime there's another popular series with a prominent blind character in a medium for blind & visually impaired folks to enjoy, it always makes me happy.
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