It's obvious that LR would do very good. Direct sequels of JRPGs tend to sell much less than the first game and LR was the sequel of a sequel. Besides, reviews hurt it a lot. If I had to choese, I'd have all FF games as stand-alone titles without sequels, like the FFI-IX era.
Maybe they should have just applied the battle system to another, new ip?
Also, i love the battle system so I may be a bit biased in this post >_<