I don't think people should be punished for posting unpopular or bad material, but why not let people be upvoted for either popular or obscure but good material? Then the karma points remain useful (and you can infer from your own recognition or failure of recognition whether they are indicating popularity or quality-despite-obscurity) but people don't feel afraid or threatened to post other stuff.
If the goal is that people should not be punished, how about the rule "do not downvote into negative score". That way it can never cost karma to post here, but people can still adjust the score of a recommendation downwards. If only positive votes are allowed, the scores will over-value controversial recommendations.
This is the monthly thread for posting media of various types that you've found that you enjoy. I find that exposure to LW ideas makes me less likely to enjoy some entertainment media that is otherwise quite popular, and finding media recommended by LWers is a good way to mitigate this. Post what you're reading, listening to, watching, and your opinion of it. Post recommendations to blogs. Post whatever media you feel like discussing! To see previous recommendations, check out the older threads.
Rules: