I've often wondered why I love to sketch so much more than taking a piece to final.  Trying to break it down I noticed that sketching is loose without the restraint of perfection.  You can create anything and it's okay.  You can create nothing and it's okay.  I've never found it interesting to finish a piece of art.  The fun of art is the creation so when a piece is finished that creation is over.  So it always seemed that although finished art is nice to look at, it's a little sad because it's lost it's potential.  However I can look at a sketch or doodle and be excited about what it could become.

I guess the downside of that is they never "become" anything without finality.