Keep it simple. It can always 'complexify' later. I'm personally of two minds.
An 'overlay' system like in Battlefront changes 'How' you do battle. I.e. complete Light Side 9-B using only characters with Blasters -- Complete Cantina 9-A with at least 1 character at full health. Win an Arena battle Ugnaught in the party.
Or - Special Bounty Nodes - where indeed you need to Herd Nerfs, keep Han Solo frozen while also fighting waves of enemies, hunt down rebel transports as they flee Hoth. Take on waves of Coruscant security while fake Obi-wan/scoundrel takes his shot. That train battle with Ventress, can't remember what episode, but perfect scoundrel fight.
Or the overlay system opens up special play nodes as well as giving rewards.
IDK -- whatever to change the pace of the game.