Sure, and some module authors have had the bright idea of using $_. If you use a module that uses $_ (or any other global) and they haven't properly localized, then maybe you should rethink using that module. For better or worse, that's the way it is in the perl world. It's true for $_, and it's just as true for %_.
You know, just because a module is out there doesn't mean people should use it. Would you use a module that didn't use strict and made all its variables global in %main:: ? I sure wouldn't.