As two others mentioned, it's more of a 9.5 game mainly thanks to studio Ghibili. You have some valid points, but I disagree with things like replay value. Not all games need to have replay value. It took me 140 hours to get a platinum. It would be ridiculous to ask for more. It's like giving a lower score to a Mario game because of the story.
As for the gameplay, sure the AI is not great, but I loved the battle system as a whole. If the AI was terrible and I ended up losing in battles, I'd agree with you. I focused on the characters I controlled and I was fine. The all out attack/defense worked well, so you could technically protect the rest of the party. To an extent I liked that they weren't that smart, because it added some difficulty and made it more realistic. None of the characters were experienced fighters, so of course they wouldn't do great. Terrible for me would be if they didn't use familiars at all and died every time when they were not defending. The AI wasn't good, but it wasn't terrible either (imo of course).
