I read or examine drafts of student work, suggest how it might be improved, and am willing to look at another draft. My eyes glaze over after seeing several "improved" drafts, so it makes sense to give me your best shot each time, improving the work in ways you discover on your own as well as following my suggestions. But . . .
1. "I did everything you said, and all I got was a B!" When I read drafts, what I am looking to do is to provide guidance on how to make the work better. When I read a final version to give it a grade, I am evaluating the work's quality. I give A's for work that is excellent, work that I would proudly show my colleagues. B's are for good work, and if I can I try to make sure that my guidance makes the work Good. C's are for work that is fair, work that has never been much improved. I believe that most students can get a B under this regime.
On the other hand, even with all my guidance, the work may not become excellent. I may not be able to help enough, not seeing how to make it excellent. The student may have chosen a project or topic that does not allow them to do excellent work. Maybe many more revisions and drafts are needed. In any case, the work is very very likely to be good, but it may not be excellent.
2. It is hard to show people why they did not get an A. It's easy to show why they got a C. A grade rubric might be useful, but I have never found it helpful for my students. What students want is a checklist that if they fulfil it, they should get an A. For the kind of courses and assignments I give, there is no such checklist.
3. More generally, rules and regulations do not lead to the best even if they are effective in marking the worst. We live nowadays in a world where there is a demand for specific rules, in the name of fairness and to penalize or avoid outrageous behavior. I just don't know what those rules should be for the work I assign, and if they existed I would be wary of seeing so many drafts since I could then be pushed to give a grade that I thought was wrong but which fulfilled the rules.
4. All of these issues come up in promotion and tenure decisions. If one's standards are not too demanding, rules will work fine. But if one is seeking excellence, they won't help. You surely want to be fair and gracious, and a set of rules will be helpful. But excellence is not well encompassed by those rules. [Similarly, you want to avoid sexual harassment, but as a dean from another university pointed out to me, you will encourage a distancing among people that may be alienating--which is fine if you don't want your professors working closely with students. (He was not arguing for sexual harassment; he was saying that the rules have some unintended consequences that need consideration.)]
5. I teach in a professional doctoral program. Its students are experienced actors in the world. Currently, there is a committee charged with reforming the program. Whatever happens, the rules in place when the students were admitted apply for them, so whatever the reform it does not or need not apply to them. But students act as if their admissions into our program is an implicit and actual contract they entered into, and so any news about the reform seems to cause a brouhaha. Some also believe that since they are paying tuition they are consumers with the rights of consumers as they understand them. Yet they want as well the authority they attribute to the faculty, to be transferred to them as they do good work. But authority is never transferred through the marketplace relationship of consumer and seller. We might invoke rules, but then we want the blessing that is beyond rules.
Again, the issue is not about being fair and avoiding outrageous behavior. Rather, it is on the up-side where decency and excellence and authority are not so rule governed, where the participants have to trust each other.