The long version, see here for my reasoning.
http://eu.finalfantasyxiv.com/lodest.../blog/3320065/

New patch, People complete the content within the week, left waiting for next patch. This is because the casual mindset does not belong in an MMORPG environment.

-Seasonal events with a difficult task.
Halloween haukke manor, was awesome.
Easter, I logged in for about 15 minutes and had everything.

-Make hard content hard for longer.
Add in stupidly hard and drawn out content that has a best in slot item at the end of it. And make that best in slot item last an entire expansion. Similar to anima weapons but it can be a simple necklace with fixed stats, highest Ilvl.
Cater to the more loyal player base.

Final fantasy is a vision of Square enix. not a Vision of the players. Make it YOUR game. Not ours!