I recently had to rest at the Inn, but only because I could not figure out how to restore my Dungeon Skills (I used up all of Gully’s smash) and so I rested, hoping for the best. Luckily that worked, but at the time my HP and MP were already completely full. Aside from trying to restore my Skills I had no reason to return to the Inn and sleep. And now, all the baddies on the map reset.
There are several ways to refill everything in the game except Dungeon Skills. You should introduce some new potions/items that will allow players to refill their Skills without needing to rest at the Inn.