The reason I don't like the turn in explanation for more caster is a simple one. If more is better, what would happen if you ran 90 degrees of caster? Obviously nothing since you'd just be laying the tops of the wheels over. You'd have no steering. As caster is increased, the angle of the tread to the ground is also increased with steering angle. Too little and the tire folds over on the outer edge. Too much and the inside edge gets all the force applied to it and the outer edge may not generate any grip. It's a balancing act. The key of course is to have as much tread on the ground at all times as possible. Even the foams you run and the tire compound can affect which amount of caster works best. One thing that more caster always does is to reduce the total amount of steering throw that the tire has in relation to the ground. That's why they say that more caster is less exit steering. It is for precisely this reason.