Well, it's only an issue for the first-time poster, and many just put up an incomplete URL such as
www.omnigroup.com to work around it. I'm not sure how many spammers it really inconveniences, as there's still plenty of spam, though it is usually removed quickly. Perhaps it would be even worse without the restriction?
The best place to report bugs is with Help->Send Feedback in the application, or email to <appname>@omnigroup.com. The forum is intended more as a place for users to help each other, not an official support channel. Omni staffers read and respond as time permits, but bug reports and feature requests are more reliably entered into the development database via the other routes, and there's no guarantee that a given forum post will be seen or acted upon by an appropriate Omni staffer.