Option to pull in all parent terms from selected vocabularies for meta keywords

I'd love to be able to specify that for certain vocabularies, nodes should publish not just the exact terms as keywords, but also all the parent terms as well. For example, I'm building a site with a pretty huge topic vocabulary, that's heavily nested. As one small example, say you've got this little subtree of the vocabulary:

History
-- U.S. Imperialism
---- WWI
---- WWII
---- Vietnam

If a node is marked with this "Vietnam" term, it'd be great if the keywords included "Vietnam,U.S. Imperialism, History", not just "Vietnam".

As a simple first step, there could be a single "Include parent terms" checkbox that applied to all vocabularies on the site. If it needed to be more complicated, we'd have to replace the existing "Auto-keywords vocabularies" multi-select with something like a little table of all the vocabularies on the site, with columns of checkboxes for "Auto-keywords", "Include parent terms", etc.

In terms of the underlying implementation, should be pretty trivial with an optional call to taxonomy_get_parents() inside nodewords_keywords_prepare().

Is there support from the maintainers to include this functionality "upstream", and if so, do you have any preference on the UI or implementation I've sketched out here? If you're basically happy with the concepts, I'll gladly produce a patch for this, since I'm definitely going to need it on my site, and I suspect it would be useful for many other sites, as well. Please let me know what you think, and I'll assign this to myself and produce a patch.

Thanks!
-Derek

p.s. Although the title sounds similar #172548: Parent taxonomy seems like it's about something else completely (though I'll admit I can't fully parse that request, so I'm not positive).