The reason for Jabari to come here is to rescue his career. He and his agent may sense his career path taking on aspects not only of Jimmer, but also of Nerlens Noel, Michael Beasley, Andrew Wiggins, Marshon Brooks, or even Carmelo (Carmelo can still score plenty well, but no winning team should want to have to rely on him.)
To stave off this sort of path in today's NBA where ppg isn't the name of the game anymore, it would really help Jabari to go to a team that teaches him a style of play that leads to winning while he's still young enough. The Jazz (or several other good teams) could save his career in the long run.
Of course that depends on him recognizing that he's on a bad path (and not just the sentiment that the Bucks haven't been good to him). I doubt he's there yet. Although I'm tempted to think the Jazz could help him now to set his career on a better path, I'm not sure that he's at a point where he'd be receptive.