Dear Geve,
Yes, that's how see it. The National Geographic Genographic project is a wonderful way for people to determine their genetic ancestry in a general, low-resolution way ONLY. Though I haven't done it myself, I would like very much to see the results the project would produce for me just as many people would.
The problem with filling in the true timeline of the actual movements of people, especially in prehistory, is that it is simply not able to accurately place people in precise locations with the required detail. The best and highest resolution method of doing this is to analyze the genetics of the human bones buried or entombed throughout prehistory from identifiable geographical sites.
Even the scientists conducting the DNA studies based on the sampling of modern populations would agree with this as the best course to take. I've yet to hear one say otherwise.
Thank you very much for your insightful and extremely pertinent questions on these topics.
Very Best Regards,
W. Sheppard Baird