With DQX those numbers are quite good considering it's an MMO.
That said I never really ever understood why Square-Enix didn't take an extra few months and add in a lot more single player content.
That way maybe you sell maybe an extra 1-2 million copies to people who just want a offline DQX, and you still get the subscribers too.
I think some type of hybrid between a regular DQ + DQ MMO in one package could've cleaned up.