I believe that your "Edit" hits the entire purpose of karma - encourage better writing. Karma for good posts. Karma for good submissions.

What is sometimes a struggle is that better writing is not always what we wish it would be. Sometimes is well reasoned explanations. Sometimes it is passionate argument. And often, highly rated comments and articles become highly rated because of timing. Sometimes it is just showing up (80% of the time, Woody Allen may have said).

It's satisfying to make a pitch perfect comment - even more so I find when it isn't snark or mean. I know what my best comments have been, and I know these are not the same as my highest rated. My best comments have been ones that I've cared about and some of those have even gone negative.