This game could be so heavily improved upon with a sequel. The combat and platforming is servicable, but can finely tuned to the likes of Kingdom Hearts and Mario without feeling like either of the two. There is only one dungeon and battle difference between the two stories and a sequel could expand on the replay value by offering more dungeons exclusive to Rue and Mint. They could use a hub town again, but personally I like exploring new towns and would prefer the game to use a map system where I get to explore multiple towns instead of one, but if they so choose to go wuth a Hub town again, there should be more npcs to interact with all with distinct personalities, stories and with quests to complete.
I found no reason to visit that church in the first game, so I'd go without that and I think the shops could be better utilized. From what I remember all that you can buy to upgrade your stats are bracers. I remember there being drinks too, but unsure if they just healed you or affected your HP and MP permanently. Buying stuff wasn't that engaging for me. I would also add the likes of Rod, Bell, and Duke for temporary party members and Fancy Mel would have to come back as well even if it's just a cameo.