Why was whaling good?

It depends on your meaning of "good"?  Whaling was great for the American Northeast because whale oil was quite valuable as a lubricant and a light source.  It gave young men a way to make money during the times they were not needed to work on the farm, as whaling season was often in the fall and winter when humpback and right whales migrated up the Eastern seaboard.  At its height in the early to mid-1800s, Nantucket and Bedford were two of the largest whaling cities in America and the town fathers indeed taxed this income, bringing other industries to town.  Whaling ships could also be commandeered in times of war--several Union vessels during the Civil War started their lives as whaling ships.  Whalers also charted new waters in the Pacific, as it was common practice to hunt all the whales in a particular area and then move on to better waters.  This is the reason I questioned how "good" whaling was, as it led to the near-extinction of the right and humpback whale.