Really it should be a core app feature. But the developers have other things on the roadmap and may not have considered this (they'll need to chime in). A plugin, if someone can develop that quicker than they can build the feature into core, isn't a bad idea - the framework for this is changing in the next major release though, so until it's documented probably best no-one puts much time into it beyond proof of concept maybe.
Has global search on web stopped needing java gubbins to work then? We are moving to Canvas at the behest of our CEO next academic year, so my development time with moodle isn't really there now, I am continuing to follow things as best I can.