I completely agree with Travis B. The special thing about Jämtland and Jamtlandic isn't so much the dialect in itself from a linguistic point of view, but the fact that the area once was an independent state (until 1178) and later autonomous (until 1500's). So from an ethnic point of view, Jamtlandic is of interest to a non-Jamtlandic person.
Jamtlandic would never be taught outside Jämtland since it is almost a nationalistic statement to talk Jamtlandic. There's no such connotation for Elfdalian. Elfdalian is merely a weird Norse language, not a Norse dialect spoken by people in a former independent nation.
Note that national borders have had no linguistic significance whatsoever in the Nordic countries prior to the early 1800's when the modern form of national states were formed. Thus, the fact that Jämtland was independent or autonomous until the 1500's doesn't mean that there was a specific local language formed. Local dialects were developed everywhere in the Nordic countries to a degree which you can't see anywhere else in Europe (given the short time span, that is).