From a defensive perspective, I think you want to stop the run to force the other team into 3rd and long. 3rd and 9 is preferable to 3rd and 2 because it makes the offense more predictable.

From an offensive perspective, it's a passing league but you still want to at least have a threat of a running game: the 4 minute offense to protect a lead or for use in play-action. You can't really be a run-first team these days unless you have a stud RB/OL and a historically good defense.