Hi Michael,
The reason why the RichTextArea doesn't have an accompanying Toolbar included in the GWT libraries is because we wanted to leave the choice open for developers and not have the RTA locked into our own toolbar.
For any developers who do want to use a toolbar with the same look as what's in the Showcase sample application, they can pick up the source from there and use it in their own applications.
However, I do see your point that it would be much easier and faster to be able to code to a RichTextToolbar right off the bat from the GWT libraries. I think the best place to make more noise about this to get it on the team radar is to report a request for enhancement on the Issue Tracker (link below).
Issue Tracker:
The team will be sure to pick it up in the next issue triage, and other community members who also want the feature can star the issue report to indicate their interest.
Hope that helps,
-Sumit Chandel