In this question I asked for a practical reason to lock votes after 5 minutes and Bill the Lizard and Arjan were very nice to explain the mystery.
Well, vote locking seems to deal with strategic downvotes fine, yet vote locking isn't a useful feature in itself. If it was the code, I would call it 'ugly hack', in a sense that it deals with a problem by creating another problem. It deals with few 'reputation optimizers' by annoying the whole community.
There's probably no need to illustrate my previous point: I've provided an example in the linked post, and there're many more complaints about it in the meta. Sure, in 99% cases you have no urge to change your vote, yet the remaining 1% is very annoying.
So, how can we adjust vote locking to reduce collateral damage? I see two options right off the bat
Simple tweak. Lock downvotes only for the users who have answers in this question.
Radical. Allow no downvotes in the question where user has posted answer himself. As Kyle Cronin puts it, This has some drawbacks, but can you really trust someone who posted their own reply to be objective about judging the other peoples' replies?.