Here's the problem, there are vigilantes using the downvote to punish upvotes by specific accounts, not based on the quality of the content. I don't think I've posted anything that could be considered spam, yet, I've run afoul of them a few times. So, no, if anything, downvoting should be more expensive than it is now. Want to combat bad upvotes? GREAT! Choose quality content and upvote, then, if you want to be altruistic, don't take the rewards. It all comes from the same pool and an upvote on other content will help to level the field.