Widgets are great to give the user control over what goes in a sidebar.
However in the case of plugins sometimes we need to get the code and control how/when its echo'd out.
Therefore it would be great to have get_dynamic_sidebar that returns the string.
The alternative would be a hook that is called after the user leaves the loop (somehow). The idea is that the plugin can run without requiring the user to update their templates. The benefits are
- User can use widgets to control the options without creating more submenus in the Settings section
- User doesn't need to be familiar with editing templates
- User can change templates without worrying that they'll lose functionality, create work etc