9. Final Fantasy IX
Criticising an RPG for having too much dialogue would be like criticising a first person shooter for having too many gunshots.
However, I've picked FF IX largely in part for its surprise "No really, this was the bad guy all along" battle with Necron. It's like the end of a Scooby Doo episode, but after the mask reveal, you have to fight another evil funfair owner.
So, you've trekked across four discs (or whatever platform of choice equivalent), made it to the Iifa Tree, bore witness to Kuja surpassing Garland and put a stop to him in the Crystal World, saving the universe.
That should be it, right? That's like, Final Fantasy 101.
You think you've saved the day, then apropos of nothing, Necron shows up. He's a force of death, apparently, though no one discusses him after the fact. It's not so much a secret boss as it is an exercise in exhaustion after you think you've beaten the game.
In reality, just call it quits after fighting Kuja. That's it, story arc over.