Some thoughts on the discussion so far:
1. The African-American Project should have a primary say in this discussion, since the vast majority of persons affected by it are the ancestors of African Americans, and African-American genealogy before the modern era is especially difficult.
2. Categories are developed by Projects in collaboration with the Categorization Project. There are often advantages in consistency across projects, but consistency is not mandatory; collaboration is. If the African-American Project could justify categorizing according to highland and lowland rather than states, it could happen!
3. If you have gotten back more than 3 or 4 generations, all of us have ancestors we are proud of and all of us have ancestors we are ashamed of, and often, our ancestors would have had different opinions on what is shameful. It is good to be sensitive -- reading colonial Maryland wills in which slavery was so.....normal....can make one's skin crawl. But in fact is was normal. On top of that there were people who were abusive. In my tree, the cousin of an ancestor was the real life "inspiration" for Simon LeGree in Uncle Tom's Cabin. In Genealogy you have to take the bad with the good. Anybody who has a Revolutionary War ancestor from a southern state probably also has an ancestor who owned slaves. If you have achieved a connection with European "nobility" and go back to the England of William the Conqueror, your tree is filled with people who by our standards would be thieves and rapists, murderers and thugs. Be historians and write about it, don't hide or sugar coat anything!
4. It's valid to call attention to the fact that their standards were not ours. I favor the use of the phrase "enslaved persons" rather than "slaves" because "slave" conjures up the subtle impression -- current at the time -- that we are dealing with people who are subhuman and therefore not entitled to marriages -- or genealogy. Read the wills and you'll understand this impression. The enslaved persons did not have family names, they were not identified by who their parent was, and you won't find a reference to two slaves who were married. At least I haven't seen any. The institution of slavery was, among other things, an attack upon genealogy, and as genealogists we have a special obligation to undo that legacy when we can.
4. Perhaps there is merit in distinguishing "personal and family" shame from "cultural shame." If I, or my parents or grandparents whom I know or knew personally did something shameful, I suppose I too should feel the shame. If my 5G-grandparent whom I first encountered in a history book or census record did something shameful, and many others of that person's generation did the same thing, that is not my personal shame, that is the shame of a culture, and we have an obligation to document it and combat its traces.
5. Despite all the newspaper headlines, I think a study of history reveals that we actually have progressed. There never really was a golden age. For the most part, we are better than our ancestors, but what we appreciate about life was built on their labor. Genealogy is always a mixed blessing. But remember this: neither Charlemagne nor William the Conqueror knew what a flush toilet was.