Seems like I recall reading that the fast angle wheel, needle point axles were designed to reduce the friction we all tried unsuccessfully to deal with as kids. You could oil the axle where it met the truck and oil the axle where the wheels mounted but the stupid thing still had so much friction that you could not pull anything that looked like a real train. By creating the needle point axle the friction problem was solved. The fast angle wheel allowed the wheel, which was no longer independent from the axle, to go around a curve.
