its very simple really, level 50 was just the initial cap, it was probably supposed to last 2 months tops, so they wanted people to be able to see the stuff they would soon be able to fight. However they put all expansion/content of the game on hold when they changed thier development plan, in all honesty, we were probably supposed to have had our second major patch update, on the 3 month cycle they used to use in ffxi, and probably planned to do here.