It's not a secret to everyone that most silly and repeated questions get most number of answers and these silly answers gets way overupvoted. So, there are hordes of, let's call them not-too-experienced participants, who never had real experience but just learned few rumors right here and always glad to paste it into 1000's question of the kind.
While really hard guestions just sink to bottom in seconds as none of these active folks ever able to understand it. At the same time to answer such a question will usually require some efforts, not just utter some platitude like "use PDO and be safe ever" or copy/paste another ugly code snippet. So, ones who spending some time (which costs money), have to be awarded more. May be even with some distinct awards, aside from shameful reputation system.
It would be nice to implement some feature that can mark questions as "trash", "trivial", "good", and "improving our knowledge".
So, it would be nice to divide Stackoverflow into 2 parts: lame Q&A site and place for ones who want to learn and exchange knowledge.
Please, don't tell me of voting system. It doesn't work. May be it would if it will take points for upvoting too, but I doubt though. The reasons for upvoting are far away from question/answer qualities. It's more matter of charity, people tend to support each other, encourage others with upvotes, no matter how stupid their answer was.