This is a short list of things which should be simple to add and would improve this game drastically. Please post anything else you can think of.

1. Working party invite system similar to ffxi (or improved). Should be able to clearly seek party and search for those seeking. Should also be able to post a msg.
Why? Because it would increase the number of ppl partying, increasing socialization, and keeping more ppl in the game.

2. Auction house or enhanced market wards which differentiate +1's +2's and +3's from normal. Should also have a sales history.
Why? Because it would help to create a more balanced and less random economy thus spurring economic activity and making the game more dynamic.

3. Linkshell management.
Why? Because not being able to kick people or leave a message makes this feel like a MMO from the 90's

4. saved ability sets. Should have a unique ability bar for each job that switches when you switch jobs.
Why? Because resetting/reorganizing all your abilities whenever you switch jobs is annoying and turns people off from leveling multiple jobs.

5. Delivery box or increased retainer space.
Why? Because it would allow people to store more goods and thus improve the economy greatly. Would also promote the leveling of multiple classes.

6. Chocobos, airships, transportation, etc.
Why? Would make the game significantly less boring. Running around a bland repetitive zone for 40 min is not what most people consider fun.

7. HNMs with -very good- drops.
Why? Creates an incentive to get good gear, spurs the economy by increasing demand for good gear.

8. competition. Could be in the form of timed nms, pvp, etc
Why? There is nothing in this game that is competitive -at all-. There is no way to "be the best" or be a top linkshell. Everything is too easy and simple. Competition is what most people play for (psychologically relative gains make humans happier than absolute gains. meaning people are happier getting more than others than if everyone gets more but the same amount).

9. Ability to continue a leve or raid if you disconnect in the middle of it.
Why? why not? you could in ffxi. And its annoying to disconnect or have the game freeze and then feel like you wasted the last 20min.

10. Pets. Summons, beastmaster, chocobo raising, etc.
Why? Because people like them. They were -very- successful in ffxi and they kind of bring a "wow" factor for new players.