it's simple. with non-ABS, you can lock the wheels during braking. the risk in this is that you won't be able to steer away from danger. this is why they tell you to pump your brakes if you start sliding during braking in rain/snow/etc, so that you can still steer and...

the other risk is that you won't come to a stop as quickly if you've just locked your wheels up and are sliding to a halt, especially in rain/snow.

with ABS, as soon as the system realizes that the wheels are locking up during braking, it pumps the brakes for you. in turn, you're more likely to steer out of danger while still slowing to a stop, or come to a stop quicker in adverse conditions.

did you count the difference for the parts that were replaced after removal? that's susprisingly heavy.