These are good points, and as the creator of SE you've undoubtedly put a lot of thought into this. I just wonder, from the perspective of an occasional answerer

These are good points, and as the creator of SE you've undoubtedly put a lot of thought into this. I just wonder, from the perspective of an occasional answerer and moderator, whether there's some way to maximize the value of the questions living in the categorical interstices. Is a question less likely to get the exposure that will lead to a good answer when it's migrated to a smaller sub-site? And some of the "subjective" questions produce fascinating discussions and enlightening answers; arguably the community moderation of such questions and answers (closing and deletion notwithstanding) still provides valuable weighting that could influence the overall graph and increase the value of the network. Could there be a shadow network still moderated for quality? Hard problems but fun to consider.