John Stewart "fans" are delusional if they think...
..that the 2011 Green Lantern movie would have been one bit more successful if all they had changed was switching out Hal Jordan for John Stewart as the lead. The problem with that movie was in its execution and lack of build-up, not in the choice to use Hal Jordan.
Hal Jordan is the basis for the entire concept of the Green Lantern Corps, the Guardians of the Universe, Sinestro, etc. Without Hal Jordan there is no Green Lantern as we know it.
Hal Jordan is the classic Green Lantern and a founding member of the Justice League. You don't throw away nearly 60 years of history because a few Millenials have some nostalgic warm and fuzzies over a cartoon they watched as kids that was on the air all of five years, because let's face it, that was John Stewart's claim to fame. John Stewart cannot carry the Green Lantern franchise on his own. Every comic book where he was the lead has been canceled within 40 issues. Every solo John Stewart project has ended in failure.
Now, I don't mind the presence of Stewart in some capacity, but without Hal there is no Green Lantern as we know it.