@believer258: The problem I had, is that the game does nothing to tell you that, yes, it is going to be a grind and the same thing over and over again. To the opposite, they build up the moment at the end of chapter 4 as the "point of no return" most J-RPGs have. So, like the completionist I am, I decided to do every quest on the map and grind my levels and all my jobs to the max. And then when the game sent me back to redo everything, although it didn't take me too long since I was completely overleveled, it still took me several hours to go around the world and redo EVERYTHING. Because, again, the game does not tell you its last chapters are going to be the same thing. It's part of the moment they are building up when you have enough of it and decide to blow up the crystals instead of saving them. And to their credit, it worked. I had enough of it and wanted to get it over with so I said "fuck it". But in the end, you still got me super frustrated with the game.
I agree that grinding for at least a dozen hours at the end of the game is inherent to RPGs, and whether this is good or bad is another discussion altogether. The frustrating part is that the game didn't need those extra chapters, and up until now, it was actually a pretty good game. It's like the game said "Okay, you had a lot of fun with this and want to see the end ? How about you play 20 hours more and maybe I'll give it to you". And that's not even particularly accurate since the game does not tell you anything about it becoming a grind of recycled content. I guess if someone warned me beforehand, it would've been way less bad since I could have decided to skip it. But again, having someone tell you "Hey ! Turn the game off once you hit the Chapter 5 title screen because it turns to crap" is not a super enthralling way to start a game.
In short: Said like that, yes, it probably doesn't sound that bad. But it's worse when YOU play it and completely sours a pretty good experience up to this point.