I too want the return of Hamlet Defense. It could work since we are taking spaces back from the Garleans and would need outposts in that process. They could attack those outposts and we have to defend them.

Yes, there were some gimmicks to them, but they could help make it feel like we really are fighting the Garleans for control of those areas. They could go full on that route by taking a cue from besieged and campaign from XI. Lose the battles and lose access to certain goods or NPCs for a period of time as a consequence. I doubt that would ever happen since we pretty much never have any consequences for any failures.