I thought a lot about this lately, and I think one of the easiest ways to make it more fun it to disable the visibility of downvotes.

I don't think it should be necessary for Steemit and the other frontends to show the downvotes a user received. Since most users on this platform actually don't understands why downvotes are important (and they are essential to balance the reward pool) we should simply not show the regular joe that he got any downvotes. Just show who upvoted you and how much money your post is currently making.