Mo Willems learned how to read his audience at an early age. He realised that adults would praise his work, whether it was good or not. But none could fake a laugh. So humour became his litmus test: If they laughed, he knew he'd hit the mark; if they offered only praise, he knew he'd failed.
Now, working as an adult for an audience of children, he knows better than to expect much false praise. Children have little regard for feelings, after all.
Perhaps that shaped this philosophy - an inspirational one, we think, for anyone with an idea they want to get out of their head and onto paper. "You are always at the mercy of your audience. As an artist I find it better to acknowledge my audience's power and get on with it."