It is not only the 747 which has suffered a fuel tank explosion, although it was the most newsworthy example. This from
http://www.b737.org.uk/fuel.htm
“To date, two 737's, 737-400 HS-TDC of Thai Airways on 3 Mar 2001 and 737-300 EI-BZG operated by Philippine Airlines on 5 Nov 1990 have been destroyed on the ground due to explosions in the empty centre fuel tank. In 1996, the very high profile TWA 800, a 747-100 mid-air explosion was also determined to have originated in an empty centre fuel tank.
The common factor in all three accidents was that the aircraft had empty center fuel tanks. However even an empty tank has some unusable fuel which in the heat will evaporate and create an explosive mixture with the oxygen in the air. These incidents, have sparked (sic) debate about fuel tank inerting. This is universally considered to be the safest way forward, but very expensive and possibly impractical. The NTSB recommended many years ago to the FAA that a fuel tank inerting system be made mandatory, but the FAA have repeatedly rejected it on cost grounds.
Boeing is now developing a Flammability Reduction System (FRS), this uses bleed air ducted to air separation modules that remove about 50% of the oxygen. This is then mixed with air from a nitrogen generating system and sent to the fuel tank to give almost inert, nitrogen rich, fuel tank air. The FAA Technical Center has determined that an oxygen level of 12% is sufficient to prevent ignition, this is achievable with one module on the 737 but will require up to six on larger aircraft.
Boeing flight tested a 747-400 in summer 2003 with a prototype FRS, data from which will be used to define the production system. A scaled down version of the 747 system was due to be installed on a 737-NG for flight testing in 2004. Boeing will then fit the FRS into some 737 & 747's for in-service evaluation after certification. A 737-200 has been also acquired by the FAA Technical Center for conversion into a fuel tank inerting system testbed.
In Feb 2004 the FAA announced a NPRM that will require a fuel inerting system to be installed on all airliners by 2011.”
Given that this is probably something that could affect any airliner eventually, I don’t see why anybody should object to the FAA insisting on a fuel inerting system. Especially on new airliners since they can design in the system at mimimal cost compared to a retrofit. Also, a 7 year notice period is hardly draconian and merely reflects the rarity of the problem.