Different tastes.
What bothers you about the story does not bother me. I also disagree that the features are 'nothing special'. True classless RPGs are not very common nowadays, and the elemental system is very well done, in my opinion.
To sum up, the game has lots of 9/10 scores because a lot of people like it. They enjoy its writing, or its hardcore rpg mechanics, or its turn-based tactical combat, or its freeform character progression, or its co-op potential, or all of the above.
You don't, and that's okay.
