These two plays are a dangerous combination because they can force the defense to respect the full width of the field.
The Runway Formation is a great formation for getting the ball in the hands of a dynamic receiver. The set up of the formation is designed to create a great surface for running the Jet Sweep to either side of the formation while also allowing for the offense to run the ball between the tackles. The result is a formation that creates run threats across the whole width of the line of scrimmage.
The setup of the formation is very difficult to defend because of the variety of different threats it poses. On the wide side of the field (right in this diagram) there is the immediate threat of trips.