Up voting and down voting that is free and anonymous might not improve the quality of stack exchange. I would argue that it encourages irresponsible and capricious behavior because of the breadth of the voting community. There are many endless and closed threads about this issue here.
If reasoning is provided for a downvote, direction for improvement is available. Giving a lot of down votes without reasoning to a newbie can be discouraging. You can even get banned from asking questions if you have too many questions that are ignored and simply not up voted.
I would like to see an AI trained to vote. Only the AI would be permitted to down vote. Humans would only be permitted to up vote. The most highly up voted questions would serve as a training set for a recurrent neural net.This is a supervised learning problem.
In a sense, such an AI would represent 'the best of the community', even if only a minority of the community actually voted. Downvotes submitted by the AI might even be accompanied by a comment from it illustrating why it gave the down vote. That would even be entertaining as well as educational.