I agree!! It would be beneficial to be able to search for such a common family name by regions. I know it would be far more organized for me if I could concentrate on message boards for Duncans in Dundee, Scotland, Duncans in New York, USA as well as other regions. I am sure that I am not the only member that would like to narrow searching down to illuminate countless amounts of posts that do not remotely address my research. It took me forever to extract any info where a family was posting about Duncans in North Carolina and their posts about family reunions.
Ancestry should realize that at some point researchers know that the people they are looking for are in a particular country / area. Frankly, I think the idea would be of help to any family name. I often wonder if my posts are even available to those in Scotland and the balance of the UK where I known I probably have family members. Also, Ancestry seems to not acknowledge the need for message boards for obscure last names such as Annal which has made my searches more difficult. Not all annals are Orkney Annals and I am related to a non Orkney Annal.