The pencil has been iterated upon countless times, by a huge number of individuals and organisations. They also have a huge variety of forms for different uses and contexts: carpenters pencils, steno pencils, charcoal pencils, pencils for users with disabilities, etc.

These factors are influenced by material constraints and opportunities, but don't discount the importance of design iteration in the simplest of objects.

And as someone who has spent a lot of time drawing, the feel and quality of different pencils (wood, graphite hardness etc.) is something people care an awful lot about.