MMO's these days cannot keep up the pace with putting out new content to keep people busy. The quickest any company can put out new content is about 3-4 months in the MMOworld, now in days a content patch might last two weeks before people begin the proverbial "countdown" until the next patch.
Used to play a game called Asheron's Call 2 and while they had problems they were able to put out a decent chunk of content monthly - they weren't raid content but it was enjoyable.