Personally, I think this update is great – if self-upvoting is false by default, it basically requires you to stop and consider why an upvote is necessary before checking it to true – instead of just doing it automatically and leaving no room for further thought.

Exactly the point, well put summary.

It's not simply a promotion of voluntary refusal to self-vote, it's effectively promoting the discourse of an honor system(s) on Steemit. And honor is a pretty darn good thing, right?

There could be an argument that honor in this sense could work for your own self interest, as it might increase your reputation, garner followers and ultimately votes. But if self voting is easier and very effective in the short term, we are going to see it I think.