Do you mean FF series used to have a Mojo? Seriously speaking, I think much of the whining comes from people blinded by nostalgia glasses. Each FF has always been different from the previous titles, and when people get older, they won't enjoy the new games as much as they enjoyed the games they played during their teenage years. To be honest, though, the titles in the FF series were always a hit-or-miss, and claims like "FFs used to have fantastic stories" is mostly a myth: IMHO, there's been at most 3 FFs with an amazing storyline. I'll go through each FF briefly.

  • FFI: great replay value with the class choices, this is the FF where I've had the most playthroughs. The game is quite non-linear too, which is nice. The storyline is almost nonexistent.
  • FFII: great storyline, but terrible gameplay. The GBA/PSP version made it tolerable, but still among my least favorite FFs.
  • FFIII: the game has plenty of nice new ideas that became trademarks in the FF series, but I'm not really a fan of either story or gameplay of FFIII.
  • FFIV: I liked the simple story and gameplay when I was a teen, but when I replayed the game (via the 3D remake for Steam), the story felt quite cliched, Cecil stopped being interesting after he turned into a Paladin, and the gameplay is nothing special. Still a classic FF, though.
  • FFV: arguably the most addictive FF in the series. Awesome battle system and gameplay, and the retranslated GBA script adds much charm to the characters, even if the story itself is quite weak.
  • FFVI: great storyline during the World of Balance, but the story practically stops after that, halfway through the game. It's interesting, though: I thought the non-linear gameplay and side-quests during the World of Ruin were the best parts of the game.
  • FFVII: the storyline was great when I first played it, and I also enjoyed the battle system back then, but I'm not sure now. The translation is quite a mess and makes the story more confusing, and the story has been retconned and changed several times in the spinoffs. I replayed the early Midgar parts, and the dungeons were even more linear than FFXIII's infamous dungeons, Cloud felt more like a jerk than cool, and Barret is a major stereotype.
  • FFVIII: the love story is forced, but at least it was enjoyable as a teen. The Sorceress story was never interesting to me. The battle system is also completely broken.
  • FFIX: probably the best FF storyline, and some of my favorite characters. Unfortunately, when I replayed the game, the battle system was terrible. Battles take 45 seconds to even get started, everything is extremely slow, actions get stuck in a turn queue, and much of the game is too RNG-based to my tastes (stealing from bosses, Ozma, Necron, card game etc).
  • FFX: my most hated FF. The battle system is good, but I dislike almost everything else about the game. The game is extremely linear, and you're mostly walking through straight roads with boring music and overly frequent random encounters with a really annoying battle music. The game is full of overly long, unskippable cutscenes. By the time you reach Luca, you know about everything of the storyline, and after that, you just watch the story unfold, and none of the twists after that really mattered to me. Tidus is the most annoying and whiniest protagonist ever, and the voice acting for Tidus and especially Yuna are completely cringe-worthy, IMHO. The minigames are also among the worst in the series: Cloisters of Trials, thunder dodging, butterfly chasing, Chocobo mini-game, the final 10 sphere hunt with icicles and a dreadful camera. The postgame is nothing but endless grinding. Urgh, this is just not the game for me.
  • FFX-2: the story is quite weak, but at least the game fixes almost everything that annoyed me in FFX. A nice battle system with ATB and job changes, and fun, non-linear gameplay.
  • FFXII: I recently replayed this game, via the Zodiac Age version for Steam, and this game is awesome! The double class system adds lots of replay value, the game's world is huge, and I really like the non-linear gameplay. The political storyline also felt much better than it did 11 years ago on my first playthrough. Oh, and the game got rid of random encounters, which was a very welcome change for me.
  • FFXIII: has many of the flaws of FFX, but not as bad, IMHO. A very linear game, and the characters are overly melodramatic. The storyline is pretty good, but the narration is weak (some details are told only in datalogs). The world of Gran Pulse is the highlight of the game, with the non-linear parts and Cie'th stone quests.
  • FFXIII-2: fixes most of the flaws of FFXIII. Fun gameplay, and relatively non-linear. The storyline is weak, but the worlds are fun, and it's nice to catch monsters.
  • LRFFXIII: the storyline just keeps getting weaker, but the open, quest-based gameplay is neat. Lightning's sarcastic remarks are also amusing. I really dislike the time limit, though. While it's not really an issue, it's still a psychological factor that makes the game more stressful to play.
  • FFXV: I've only played the demo (1st chapter), and the game didn't seem like my type of a game. None of the characters seemed interesting to me, and for most of the time, you were just running through huge, empty areas. Supposedly the storyline is quite rushed, but you can't really blame the development team. After Nomura got practically nothing done in 8 years, the team pretty much had to create the whole game in 2 years or so.