Well one good thing about dark side is that it makes it really easy to 3 star the cantina nodes, because the debuffs are just so good at stopping the AI in its tracks. I 3 starred the last cantina node (8F) with my empire team, and I haven't even beaten light side normal 9A yet.
Also I feel that dark side requires a completely different play style as oppose to light. With wiggs, its all about absolutely murdering your opponents team. With chaze, it's about never dying, and taking the enemy down slowly. With Jedi, it seems to be about all those buffs, and the same as chaze if you run bariss zeta. With empire teams, the goal is none of those. The goal is to control the match by debuffing your enemies to the point they can't do anything, giving TFP/Boba the time they need to pick the opponents off one by one. Control the match: and victory is how I would sum up the dark side, while murder or outlast is how I would sum up the light.
Other than that, there isn't much reason at this point to play dark side. It's great fun if you don't want to follow the meta I like to call 'Rebel Scum' and play in a different way, but other than that there isn't much reason to go to the dark side. Honestly it needs some more love and reason to go there (even resistance got buffed and is now decent).
