IMO, airport runway length is a result of what an individual airport businesses are, e.g., if they are a major airfreight hub besides passenger service, the runways will be longer. Also, in the USA, some commercial airports once were military air force bases or even today, serve both functions and some are at high altitude and can be hot during the summer months such as Denver's airport.
I have attached an airport master planning review for the Dayton, Ohio international Airport that discusses in some detail runway lengths based on aircraft. Surprisingly the recommended runway length for a B737-900 series MTOW is 12,800 feet (3,900 meters).
http://www.landrum-brown.com/MasterP...t%202-9-05.pdf
Also, the FAA gives design recommendations and requirements for runways in the document below:
AC 150/5325-4B - Runway Length Requirements for Airport Design - Document Information
At JFK International, the most used 14,572 ft (4423 meters) runway 13R/31L was intended to be a backup runway for the Space Shuttle although it hasn't been used for this purpose. It was recently repaved in concrete and widened to 200 ft for the Airbus A-380.