We have no plans to change from the current custom-initialization method for bundles adding selectors to the Select menu.  Bundles that add to the Select menu may want to do some pretty complicated things that would be difficult to describe as tags in bundle_info.xml.  For instance, the atomic bundle dynamically populates the Select→Chains menu on the fly as the menu is posted.  Though ideally it would be nice to reduce startup overhead by not needing to execute the bundle’s custom-init code at startup, there won’t be that many bundles that add selectors, and the Select menu gets used often enough that the overhead won’t be “wasted” in most cases.

—Eric