To go into a bit more detail of what I'm trying to say here. Ultimately, what I don't want is that sense of repetition. Repetition is in a lot of games today and button mashing is just one example of it. Covering stuff like this up is a game designers job as it can be a distraction, and even ruin, the whole entire experience.
As for the battle system. Sure, being able to do other things such as casting magic might help. For me though, it's a bit more then that. It's the entire game itself. FFXIII was repetitive not just because of the battle system but because of how the entire game was structured. All you did was fight, fight, fight, fight, fight with really nothing else to do. Things like exploration, back tracking, mini-games and doing side quests for example could help break that repetition, but there wasn't really any of that. All you did is fight. The game was devoid of content. Because of how the game was structured, it ended up effecting the battle system. Auto-battle or not, the sense of repetition was there. I felt it. I wasn't excited fighting enemies. Instead, fighting the enemies in FFXIII felt like a chore with no sense of reward.
So it's not just one thing, it's many things. All things should work together as a unit. If one thing doesn't work well, it can end up effecting things that do work well.
And yeah... We do a lot of fighting in previous Final Fantasy games as well, but it was disguised well and that's the key. Hopefully FFXV does the same.