I'm fairly certain they use Nitrogen in aircraft tires, due to the wide swings in temps (from a cold gear bay at altitude, to the "burnout" at touchdown). I think the rationale is the pressure changes due to temp variance as mentioned earlier with the attraction of water with compressed air use.
On a car, it's just an "overblown"
safety feature. Honestly, we should be checking our pressures more often instead of relying on an inert gas for a safety margin.
RH77