I like the notion of a keyword system, but if the keywords are user-selected, why should we expect the results to be any better than our defacto (almost) keyword system of asking perps...   uh, 'posters' of new root nodes to create clear, relevant and searchable titles? (Well, yes, I know we don't ask for the "searchable" but I think the frequency with which "haznav" crops up in a consideration for a title change

1. ...seems to suggest that search-ability is a desideratum.
         and
2. ...provides unambiguous support each of your second para's conclusions ...BUT at the same time suggests the extent to which users post weak, ambiguous or flat-out lousy titles is a reason for concern.

But trying to write an AI process that would provide better titles is a challenge I'm not about to enlist for, and I suspect is too big a challenge and task for Monks who lack as huge excess of spare time. To that extent, a clearly labeled section for "Related topics"   -- ( as suggested above )  -- seems to have merit, despite the number of times it's been rejected.