I don't know about traveling just for traveling's sake (because repetition), but adding content outside of fates into the open world will get the same desired effect. Hidden NMs that dont require a giant mob to kill and drop something actually interesting can definitely spice up the open world. That or open world dungeons that involve puzzles with doors/levers/etc. Then it can instance out to a boss fight or w.e. We do that similar to the treasure hunts, but the involvement with them is very shallow. You're just walking on open land and popping a chest.

My biggest gripe of this game is we have a giant beautiful world here and it has zero use after you go through the story. I would like more implementation to actually give any and all players a reason to go into it. How neat would it be to travel into all this ocean/lakes we have in content and find a cave that leads to a small puzzle or something?