An expression of who we are. So if people ever tell you you shouldn't create, or ask you to justify your creations, tell them to justify the rain falling or the wind blowing. Those things don't need justification, and neither do you. I don't think I have ideas. I think ideas have me.
Expression is great.
But sharing is part of an artist's life as well. We're social beings, and communicating ideas is part of that. Our creativity is something too much fun not to share with people. This is a difficult area - to some, communicating art is as much fun as creating it. To others, there are barriers in skills and personality to sharing creations.