There are several reasons to write questions of HubPages.
1. You can earn accolades for asking questions.
2. You can earn accolades when enough people have answered your questions.
3. It does influence your HubberScore because it shows your activity in the community.
4. It can lead to people finding your profile and hopefully followers.
5. It is a great way to get questions answered about HubPages. I have found hubbers a lot more helpful in learning about hubpages than the HubPages Learning Center.