I think that we sometimes confuse the "longing for new ideas or forms" with the fact that we are merely bored with what we are doing. It is pottery's challenge to us, to make it well, and to do so over and over again. So we repeat. But with repetition/reiteration comes staleness/boredom. It is good to be restless.
Every morning I have 2 soft boiled eggs. I am comforted by this habit, not to mention satisfied by it. What clicked in my head yesterday to change that habit was risky in a way. It risks the comfort, but it promises a payoff, maybe something exotic. The real motivation, or as Ron puts it, "longing", is boredom. Boredom with one's work is not necessarily a negative thing. Not recognizing when we are bored is. This recognition is as critical to making fresh work as an an egg is to one's sustenance.