From my play time with FFXIII and the demo of FFXIII-2 i would say the score is a bit harsh but not uncalled for.
That combat system was and will always be the downfall of the game. Its too incredibly boring. All auto attack and change paradigms once in a while to defend against a major attack or heal. There are basically 3 commands you have to master to play the game. Imagine playing a game of rock-paper-scissors for 40 hours. It gets boring.
Once the gameplay falls short like that, wether you have a good story or a living world, will always fall short. FFXIII was a terrible game that deserved 3/10. FFXIII-2 does deserve somewhere around 6/10.