Basically, a lot of JRPGs have easy normal battles because the challenge for the player is supposed to be managing their resources so that they can get through the dungeon. It's kind of like survival-horror, but with Chocobos.
By making sure players will always have full resources, and making sure death isn't too heavily punished, they seem to be designing a game that will require a lot more live-or-die strategy in each regular battle. Basically, every battle can be like a boss, and won't have to be easy enough that players only expend a small percentage of their resources in it.
If they can follow through with this, it could be great.
Only controlling one character sounds really lame, but I've read a couple of interviews where they suggest there are ways of the controlling other characters which haven't been revealed yet.
I'd be happy with good AI and the ability to switch characters on the fly. Though if this battle system works I hope they try fitting it to more traditional ATB party control someday.
