Air travel today is slow and frustrating.  For the first time in history, the average speed of travel is decreasing.  Large portions of days are wasted fighting traffic to and from distant airports, and in security checkpoints and gate changes.  Many airports are at capacity, and the hub and spoke travel system exacerbates delays. 

Airports and runways are choke points that delay and degrade the travel process.

Building new airports and runways close to urban centers is a practical impossibility.  There are currently no other feasible plans to accommodate the growth in air travel or alleviate the dependency on runways.