I think a lot of the downvote abuse is cultural, as in it wasn't available before and now people have been finding their feet with it. When it comes to "dislikes" on other platforms like reddit, it isn't an issue. The problem on Steem is that there is an economy, and people often think that once a vote is placed they own the value of it, without considering the 7-day payout. There has to be a negotiation period due to the shared nature of the reward pool. Given time, I think the process would normalize and most of the darkside would disappear.