DQX sold phenomenally well being a MMO; the service just leaves way too much to be desired at this point. Once you beat the 'final' boss you're left to grind all your jobs as many of the passives transfer across classes (you can have a 150HP/60MP/150atk level1 character, for example), and the system lends itself to grinding the same mobs as the most efficient method. There were probably more people than SQEx expected that blindly followed strategy websites (極限攻略 to be specific -- the site's made a name for itself w/ guides on Dragon Quest games over the years) and didn't do any "adventuring" of their own.
Horii wanted to make a DQ MMO while Sugiyama was still able to make music. It's actually a fantastic game, just that there isn't the lasting power there to keep people playing beyond the first 2, 3 months.