Maybe it would be a good idea to have an option so webmasters can choose if they want auto-update for Xtreme Plus. This way everyone could install manually what is required when login to admin panel. We could benefit earlier from the latest updates.
Admins always have the choice if they want to update a plugin or not, and that includes Xtreme Plus.
This particular situation of having functionality in the theme (1.1.2) required by the X-Plus plugin should be a fairly rare occurrence. Normally, new releases of the plugin will be able to work with the current version of the theme. This time, the changes required to support the new SmartMenus in the theme was fairly significant, involving changes to the CSS for the standard menus so that either menu system can be used. This normally should not be the case.