This raises an interesting point that maybe relates to what the whole purpose of Categories really is. On the one hand, place names as they were at the time has value, as documents and such from the time are going to reflect those names. On the other hand, putting the place names of today gives some guidance as to where to go for research and documents and so forth.
I do rather cringe at the thought of tracking all the various regions of the United States through history, in particular. I have an ancestor who was in the region when the Wyoming Territory was founded, and then again when it was converted into a state, so do I need to link him to wyoming as a state, and wyoming territory, and dakota territory? Or just put him in the category for the county, and the county ends up in about 15 different categories? I'm not sure there's any value at all to that, aside from being historically complete, no one's going to use those various territory categories if they're just putting people in the sub-categories of towns/counties/etc. Similar goes for land in the original territories - I have an ancestor in Maine in the 1630s and his lineage continues there for about 200 years. Are we really going to create categories for all the various names of land patents and track them through time, such as the Gorges Patent, the Province of Maine, the Province of Massachusetts Bay, etc? I'm not sure it's useful - I'll end up with some ancestors in "Saco, Maine" and some in "Saco, Province of Massachusetts Bay" and some in "Saco, Province of Maine" and some in two or more of them.
I guess what I'm saying is maybe the "time dimension" needs more thought and discussion; the rules outlined above are a good starting point and can be adopted where they apply right away.