Your idea is being implemented by radi in osm2city, which could be extended to include all objects in an airport. In this case, runways and taxiways would be objects as motorways and railways and streetlamps and power lines are objects in osm2city. The main problem is that it could take years to get to the level of quality we have now using data from the apt.dat: ligths, shaders, line features... Check this example of the current state of osm2city: viewtopic.php?f=5&t=22809&start=150#p221705
In addition, there is not anything wrong with the apt.dat approach. The main problem is we may not have access any more to the data and that, currently, airports must be built offline. X-Plane builds airports on-the-fly using the apt.dat, and it is easier to upgrade them. Maybe we should aim to the dynamic creation of airports, but I feel it is not going to happen in the near future due to lack of man-power.