I don't necessarily think that seeing down-votes would lead to some people's (at least my) adjusting their Hubs according to down-votes, because people vote things up and down for their own reasons. Nobody is going to please everyone all the time, and I've seen that if a Hub expresses ideas that are in the minority, there's a good chance it will be voted down; even if, in fact, the ideas are well founded, researched, accurate and presented in decent grammar.
We can't stop people from voting things down for their own reasons (and "quality" is often subjective anyway). Neither would I necessarily want to stop people from voting things down. At the same time, I'm not about to adjust what I've written because someone else (or a lot of someone-else's) don't happen to like it. I can accept less traffic and less earnings if that's the case with an unpopular Hub, but I don't write based on votes; and I don't change what I have to say either.
I think the "win/win" situation needs to go on between the writer and the individual reader; and that goes on when the writer does his best to produce decent quality writing and remain true to himself and his own aims as a writer and as a person; and when the reader sees that (whether or not he likes the style/ideas of the writer; or an individual Hub).
Besides, I think most reasonably capable Hubbers know, exactly, which of their Hubs are weak and which are solid. If someone isn't capable enough to recognize that there's a good chance he won't be capable enough, either, to fix any voted-down Hubs anyway.