It is the whole "I don't wanna get caught flagging" thing going on. It would be interesting to see what would happen if there was a way to program in a kind of deflector shield that prevented against retaliatory downvoting. It would be tricky to implement, but theoretically worth discussing.
Incentivizing the good content and curation is one thing, but bot votes aside, we are still left with the problem of self-voting at a whale level. And I think @blocktrades says it best. Incentivize curation of others bringing it back to a 50/50 split of curation rewards.
At the VERY least, it will break up the earning capacity of the bigs, and leave more for us littles to swim in. If we can take a breath and see the bigger picture, we won't be annoyed by our lack of self-vote points.