Okay, I'll just answer stuff from memory.

The gameplay is simplistic. The systems of VII and VIII might have been easy to abuse, but that was because they rewarded players who knew the game. I know IX pretty well IMO, but getting anywhere is simply a task of repetition. Two discs with no character choices or real ability choices is a long time.

The mini-games. Stellazio hardly counts as a mini-game. Chocobo was good. Cards, Hippaul, skipping, Mognet, were all pretty long and pointless. I can't even remember the hourglass so it can't have been that special.

Linearity. Of recent games only X gave you less choice of what to do or where to go. VI was unbelievable with freedom. VII wasn't quite as free, but still a long way past IX. VIII was linear, but there was still a reasonable amount of choice, and the flexibility of the game countered this.