That certain song single-handedly makes your statement untrue, in the case of Blue Dragon. I still have nightmares about having to listen to it. :|False. Blue Dragon and Lost Odyssey are the man's greatest achievements.
Still, even if those two could be considered his best work (the whole OST of VI & a lot of stuff from VII & VIII like Liberi Fatali, Aerith's Theme, The Man With the Machine Gun and such are much better, imho), they've got nothing against Sakimoto & Hamauzu's best work.