Not sure if its a good idea, but would it be possible to run the game solo (I know you can't beat it without your allies) as in disband the party or will the game solely focus on the trio main characters?
Story wise yes its a must have, but revisiting cleared areas solo (even at level cap) might be interesting (I'm not hating on the characters too just fyi), and whenever you need em in order to progress the story or whenever you feel like running places and defeating enemies together you could always rendezvou back at the mercenary camp, just a thought