It's about context.
When your passing game is Drew Brees throwing to Colston, Graham and Meacham, throw the ball like crazy. When it's Aaron Rodgers throwing to Jennings, Finley and Nelson, do the same. Tom Brady throwing to Welker, Gronkowski and Hernandez...well, you get the picture.
When you've got Ryan Fitzpatrick back there and a ragtag bunch of receivers and TEs, AND your two most explosive players are your two running backs, you run the ball. Whether it's a passing league or not.