And yes, changing the location of the end of the steering arm can alter your toe change curve. But when you're adding caster with eccentrics you're never just changing a single spec. So, it's not a given that you're always adding bump steer by adding caster, you're not making a single change so it's not simple. It depends on ALL of the other alignment specs, in addition to the ride height. Adding negative camber can change the bump steer, lowering the car the can absolutely change the bump steer, changing the bump stop heights can change the bump steer curves because you're altering the angles on the upper and lower control arms and the steering arms by changing the travel range, etc.