There is also the challenge aspect. Being able to capture a clear detailed image of a part of the moon that is perhaps only clearly discernible occasionally is probably very satisfying (i don't know for sure yet as I haven't managed any clear images of the moon at all!).
A bit like achieving a target on a bike ride (first century. making it to the top of a bastard climb for the first time). You may be alone and no one else sees you triumph but it is still satisfying none the less.