I personally don't see much difference between scatter and bubble charts, I actually never use any of these either.
On the other hand, I think a treemap would be much more useful, here is an example:
Could we add this format as an option (additional or replacement of scatter or bubble)?
This is a really good idea. Especially for the Site Section report. With a treemap visualization it is easy to see the comparative sizes. And if you click on one of the blocks you would see the sub site sections.