I don't think we really know enough about the story to say whether it's convoluted or not. When only bits and pieces of a game have been revealed, it's obviously not going to make perfect sense. If they gave away enough for you to know exactly what was going on, then the plot would be spoiled before you even got the game. And, while all the games take place in Ivalice, they're all different takes on the same world. So you might see some similarities and homages to the Tactics games, but I seriously doubt there will be any sort of substantial connection.