Currently, runways are repaired by simply pressing a repair button. The simulation fidelity here is quite poor, and can be improved.
First, the runway degradation should occur much slower, since it would be a much longer process to repair a runway. The service car, or a new vehicle can be used to repair the runway. The idea is that players must plan ahead for runway shutdown. They must close the runway, and send a service car to the runway to repair it. This will require more planning for the Airport CEO.
Why it should be implemented:
This should be implemented because it adds more realism to runway degradation. Currently, it is simply a nuisance since all you have to do is press repair. It is in the way, and does not add any simulation or quality to the game. The new system would encourage people to plant more runways, to plan ahead, and to have to close the runway for repairs.