I'm not comfortable with the OP's post because I feel he has gone beyond the ethical discussion of why we vote into advocating for constraints on how people should assess value. Each of our assessment of value is a private right. It is the very essence of voting. If that is what you mean to say when you proclaim "and by rights there shouldn't be any" I agree.
There is a saying where I come from "With the simpleton... with him, you must begin to ask the questions for him." One reason why bad nodes get up-voted from time to time is that we don't all assess intent or hard work the same way. One person's perception of laziness is another person's perception of an honest struggle to ask the right question. Where one person sees condemnation, another might see cause to give the benefit of the doubt.
On the other hand... :-)
At least part of the OP's intent is to remind us to take care in our votes, however we choose to use them. With that goal, I agree wholeheartedly.
Do you really, really mean to say that all discussion of the motives and reasons for voting is over and done? It never needs to happen again?
Not every vote is cast with the intent to assess value. Votes can be cast for favoritism or anger. They can be cast for XP bonus or the XP can be used as incentive to read and learn more by spending time searching for nodes worthy of a vote. Votes shape behavior so they do have moral implications. If my action has the potential to influence another human being, isn't there some connection between moral choice and vote? Doesn't that part of the discussion need to happen again and again from time to time?
If having a discussion on how we use our choices meant it never had to be had again, I suppose we could throw out nearly all of human moral discourse. There are certain kinds of conversations that do need to be repeated because they are based on values and choices that can change, be forgotten, or need to be reassessed from time to time.