Why is Qui-Gon Zinn not meta?

Because Jedi are in desperate need of a rework, basically. Many are literally years behind the power curve now - including Qui-Gon himself, whose zeta is his main redeeming feature at this point. The only ones that see any use today are General Kenobi, Old Ben, Ezra, Hermit Yoda, and zeta Barriss, and they don't make a coherent team together or with Qui-Gon, since it's two tanks, two healers, and only one real damage-dealer.

You'll see the odd Jedi, especially the Kenobis since they're two of the best tanks in the game, on non-Jedi teams. But you won't see Jedi teams standing up to the current meta until they get a rework and/or new characters.