uninstall is uninstall is uninstall. It is not partial uninstall, it is not a maybe uninstall. User wanted an uninstall, and even if the user is an idiot you should respect his wishes.

If external tables are not deleted why should anyone assume that options and such do get deleted? Unless it is a bug or oversight, it is a good sign to stay away from the plugins that do it.

Some things are hard to delete, like media that was specifically associated with the plugin, but that should be a very small exception to the rule of "delete everything on uninstall"

Actually it should double apply to storage of sensitive information like financial transactions.