One important thing to note is that - due to the nature of Tridion development - questions on this StackExchange site are likely to be (in general) broader in scope than questions on another StackExchange sites, such as StackOverflow. We are likely to see many more questions of the form, "How to I accomplish x," and comparatively fewer of the form, "Why doesn't y work?"
This has a couple of effects. Firstly, there's likely to be a longer period of time between an answer being posted and accepted, because the development work between the two events is greater. So, perhaps it's just a matter of patience.
Secondly, because questions are broader in scope, you're likely to see a wider variety of answers. This means you're also likely to see some very high-quality, detailed and "well-voted" questions going unaccepted. In my opinion, however, this is no bad thing. The fact that an answer didn't provide the eventually-implemented solution to the initial problem does not mean that it is without merit, nor does it mean that the answer didn't help to isolate a solution, nor does it mean that it won't be helpful to others in future. All of this leads to us having a varied wealth of information posted under every question, which creates an excellent resource.
Perhaps the issue, then, is trying to encourage people whose problems weren't quite solved by one of the provided answers to come back and post their eventual solution.