Hi there,
I've had a few folks that I work with try to embed Tableau visualizations in their Omeka sites, and those haven't been working because the tags keep getting stripped out. I've tracked down the problem to the "media" plugin for TinyMCE, and I've taken it out for the sites in question. I had to do this again in Simple Pages, because the plugin configures TinyMCE for the add and edit pages individually.
The bigger question about the media plugin itself might be a pain, from the limited Googling I've done, but it would be great if Simple Pages used the same TinyMCE config as the rest of the site.