Hi pepperstreet,
Comments are strongly related to a user, and what's cool with User Notes, is that you can natively view/access them directly from the User manager.
Also, comments don't require a "Content view" or "routing"... that's why we've chosen to use User Note object for our Comments App.
Thus we keep the #__content table clean.. and ready for new Items that really need to be "Articles".
Finally, we thought it was nice to introduce a new Object plug-in for SEBLOD, to show that we can really integrate with any Joomla! component.
Regards,
Saba.
PS: of course anyone can build his own Comments App based on Article object or even Category object is needed...