it's not just Final Fantasy really, most of Square-made games have absolutely garbage sidequests by principle it's absolutely not worth investing other than to 100% complete them.
They wouldn't be so bad if most of them weren't so pointless to complete. Either it's so close to the end of the game it doesn't matter any more or it requires so much time and effort by the time you finish it it doesn't matter anymore or the rewards are just completely underwhelming and worse than things you get by just playing through the main game. That type of thing isn't even just limited to square games or jrpgs though. I don't understand why games bother including super secret special anything right at or after the end of the game when it's pointless to even bother with it. It's not so bad in games with a meaningful NG+ or good post game content but not a lot of games actually do that well either.
On a more general note, I can't stand side quests that require waiting for arbitrary amounts of time, this includes waiting for things like regenerating resources or crafting or whatever to complete. Even things like the biggoron sword in OOT annoyed me. Majora's Mask was less annoying because the game was built around it but some of those side quests, Kafei, had a lot of pointless waiting.
Anything collectible related. No i don't want to find 200 shiny thingamajigs scattered around every nook and cranny of the game. I count quests like 'kill x monster y times, or 'collect x many of this item' as the same kind of thing.y
I don't really like community puzzles. The ones in games like Fez and Animal Well. I'm sure they're fun if you play the game brand new when everyone else is figuring it out but if you miss out, you're basically just going to be solving them with a guide because there's usually no way to actually complete them by yourself.
Some more specific ones I didn't really like.
The ring sidequest in the Oracle Zelda games was pretty awful. I owned Oracle of Seasons and I think if I remember right I ended up renting Oracle of Ages and then playing through Oracle of Seasons again just so I could do the password thing and finish the ring stuff and get the full ending. I never finished Ages because I didn't have the game for long enough.
On a similar note I'd count any of the stuff that required a link cable and a copy of one of the other pokemon games. Finishing the pokedex, Pokemon that evolve only through trading. Stuff like that. They're not really side quests but you don't need to do them but the game rewards you for doing them so I feel like they count.
Actually, basically any game with any side content that requires you to have another, different game or some special peripheral to complete is some complete bullshit that exists just to sell more games.
I didn't like the delicate flower quest in Hollow Knight. It's stupid hard to try and do it properly but easy to cheese by just clearing a path all the way from the flower to the npc and not resting on a bench.
