The statement, "The War of 1812 was not primarily fought over the issue of Impressment", is correct. Several other incidents also contributed to the war not just impressment. A major cause that found support among the settlers of the West is the fact that the British were supplying and aiding the Indians on the frontier. This cause was found to be true especially after the battle of Tippecanoe(1811). At this battle, the Indians lost and left their supplies behind them as they ran. The supplies were of British origin and caused an uproar in the West.
    Another cause of the war  is land. The War Hawks wanted to go get more land especially British controlled Canada and Spanish-Florida to add more states to the Union. The reason they wanted this is because it would deny the British the Indians on the West to incite, hence saving lives. Also, it would control and deny the marauding bands of Indians, thieves and, run away slaves the Spanish Sanctuary in Florida.
    The last cause was to get revenge for the British insults. Britains Orders-in-Council not only blockaded American ports for the purpose of searching and impressing American sailors and bottled up our trade with France and her allies but the British then went ahead and captured about a 1000 of our merchant vessels already in Europe when the Orders-in-Council(1806, 1807) were passed. Plus, the British had insulted our free navigation of the waters when on two separate incidents they fired into an American navel vessels.
    The first one is called the "Chesapeake Affair"(1807). In this incident the American ship, Chesapeake refused to be boarded by the British ship, Leopard. The British then proceeded to open fire on the Chesapeake, killing three. The second incident is the "Little Belt Affair"(1811). When the HMS Guerriere had impressed a man from Maine, Cpt. Rogers of the USS President  was sent to get his release. The American ship, the President tried hail a ship called the HMS Little Belt, whom Rogers thought was the Guerriere, the Little Belt fired a shot at the President. In the sharp battle that followed the HMS Little Belt was disabled and suffered 32 causalities. Both of these incidents were in sight of American land. This proved anything was liable to come under a British hail or fire and gave strong support for war.