Think of it like this;
ABS makes the brakes act the same way as if you trained every day at making panic stops.
Think of how good you would be able to brake, if every day, you trained at threshold braking, at bringing the tires up to the limits of adhesion, in dry, rain, dirt, sand, shell...
The average rider will never be able to outperform ABS. We had a very experienced rider, Fred H., who some may have heard of here, if you ride a Gold Wing or Concours. He is not a racer, but he has a lot of miles under his belt, and a lot of experience riding fast. He made a bunch of stops with ABS, and then disabled it, and did his best to beat it. This was on dry pavement under ideal circumstances. He could not beat the ABS.
Have you ever made your tires sing, both of them, on dry pavement? I have. Without ABS, that is a heart-stopping moment, but at the same time, one to make you proud, at least if you don't drop it... I can do that at will with ABS, and it just brings a smile to my face, no heart stops.
If you have ever practiced threshold braking, you know that it takes a lot of concentration. That concentration is better used elsewhere in a panic-stop situation.
I have not used ABS, "in anger" or when it counted, on a motorcycle. I have used it in a car on one occasion where I am dead-certain that it saved my car, and possibly my life. I have used it on several other occasions where it simply took a high-pucker moment and made it into a no-pucker moment. You almost feel like a god, when you slam on the brakes to avoid the car that spun out in front of you, see that you are falling back from them, so you can look in the rear-view and ease off the brakes because the guy behind you is about to rear-end you. You modulate the brakes to hold yourself between the two vehicles, not worrying about locking up and spinning out.
Basically, what I'm saying is that ABS gives you a major edge that is often neglected in these discussions;
1; ABS allows you to concentrate on situation awareness during a panic stop moment, rather than concentrating on braking.
2; ABS allows you to initiate braking as quickly as you can pull the levers. That saves time "creeping" into the threshold zone. This saved time is when you are moving the quickest. At 60 mph, 1 second is 88' traveled, so if ABS lets you get on the brakes a 1/4 of a second faster, you just saved 22 feet, at 60.
It is often mentioned how ABS can be bested by highly experienced riders. The problem is that we are talking about the best riders in the business, and they are given multiple tries to beat the ABS. The real world ain't perfect, and you are not going to get more than one chance, when the stuff hits the fan.
For the average rider, who wrarely, if ever, achieves maximum braking, the ABS is going to cut down on the stopping distance from the moment the brakes are activated AND from the moment YOU REALIZE YOU NEED TO STOP. The second one is huge. ABS cuts down on your reaction time because you have no anxiety about dropping the bike due to locked brakes, and you do not have to "creep" into the zone.
Many people say that, if you are aware of your surrounding, and ride safely, you won't need ABS. Well, guess what? The average rider has moments when they are distracted, and when they are not aware of their surrounding...
More than a few people have dumped the Burgman due to locking up the front brake. For them, ABS probably would have paid for itself in one use, if only for the cost of the tupperware, and the mental anguish that a dump causes most people.
ABS will not save you if you grab the front brake in a sharp turn. ABS does not repeal the laws of physics. ABS will not make you rich and attract a desirable mate to you. ABS will shorten your stopping distances in the real world, and that might save your tupperware, life or hide. ABS will allow you to increase your situational awareness when the stuff is hitting the fan.