I thought the OP had a very reasonable suggestion. It would be very beneficial to me to have it as a profile setting. And if for me, then probably others, too. So only those who want it would change their behavior.
2) You can't "burn" downvotes. You have as many as you want, but can only downvote any eligible comment a single time. I can't remember what makes some comments ineligible, though.
3) You'll end up hating HN if you take downvotes personally. Downvoting is often a way to say "I disagree" without polluting the thread. Sometimes you hit a seam of (dis)approval, and there's no rhyme or reason to it. I hope a few downvotes won't stop you from participating, as there are a lot of brilliant people here who have interesting things to say.