Its the ease of hitting 50. People race to the end, finish it, and then move on to something else, because they are (temporarily, at first, then that morphs into permanence) done with the game.

Any game where the majority of players can reach max level in their main class within the 30 day trial period is not a game that has real lasting power for that same majority of players.

Quite honestly, though it is way too late to fix it, level exp should be 10-20 times what it is right now. If going from level 21 to level 22 takes 63,900 exp, it should be somewhere between 639,000 and 1,378,000 exp.

The faster people reach "end game" the faster they devour that content and leave. Of course, that has to be balanced against the perception of the amount of "work" that it takes to reach that "end game" - which means that the game has to be fun at all levels, not just the very top, or people leave before reaching that point.

Personally, I expect to be here for 2.2, but not for 2.3.