What I would love to see, and may be hinted at by the lack of experience points and the importance of weaponry (the many different types of weapon) is a system akin to Monster Hunter.
There would be no experience points, because there aren't even any levels. The only difference between a master and a novice is their equipment and the players's skill. Of course, in an MMO like Final Fantasy XIV, there would be more to it; abilities, weapon skills, magic spells, etc. These would all be attained through quests, however, rather than simple level up and only if ones skill in a particular weapon type meets the requirement for said skill or quest.