The content in the "main page content" block already has its own wrapping divs, whether its the node or panel or View, whatever. Adding a block wrapper around it is redundant.
The content region is already placed in a div#content so that can be placed in the same column as the title, help, tabs, etc. So adding a region wrapper around the content is also redundant.
We can easily get rid of these wrappers by creating a region--bare.tpl.php and a block--bare.tpl.php that have been stripped of their wrapping divs and then adding a template suggestion for the main page content block and content region.