That's an excellent question.
Last year the Quebec government set up a commission to study tax measures which apply to the regions and which is commonly known as the Gagné Commission. The commission found that in remote regions productivity rose far more slowly than in urban and central areas. In Quebec, productivity rose 2.5% between 1998 and 2005, 3.5% in metropolitan areas, and 0.2% in outlying regions, what you call rural regions.
The members of the commission found that what pushed productivity up was cutting-edge businesses, companies carrying out second and third-tier processing, and generally any enterprise with a great emphasis on value added. They also found that the difficulty in attracting skilled labour in remote regions prevented them from opening high tech or processing companies. So the purpose of this measure is to avoid that kind of situation and to deal with the problem of underproductivity in the most remote regions.