complacency

If there's one thing I've noticed in my endevour to become a better artist in any sense of the word, it is that the process of becoming better never ends--there is always more room to become better. As such, the one thing that has the ability to end art is complacency. How do we create when the burning desire of inspiration dwindles to an ember of self satisfaction?
It is the insatiable hunger to better one's self that creates new and better art, and is why the painter continues to paint, or the writer continutes to write or the singer continues to sing. So what do you make of a singer that ceased to struggle for better music? When a group of singers get up and sing the notes on the page instead of the music that was intended, how do you combat that without being accused of being to tough or "mean?" What do you say to people want to sing but don't want to listen?