A lot of questions asked here are such that even if a good answer is found, it probably can still be enhanced.
On occasion, it makes sense to accept the best answer, but still it's quite probable that someone could (even easily) write a better one. A good example of this is Biblical basis for the separation of church and state. Almost anyone who personally uses the Bible to argue for the separation of church and state could probably write a more in-depth answer. Still, the current best answer is good enough for now.
Should there be a way to request further answers, or is it just common sense that any 5-year-old question can be dug up and reanswered?