As an owner of a 1150Gs BMW with ABS, I am in love with the system. For a heavy bike that spends a lot of time on the freeway it's an great feature. Knowing you can just grab a fist full of the from lever if something is in the road or someone cuts you off is a great thing.
I would however never want such a system on my sportbike or my moped. Lightweight bikes with strong braking systems make stopping on a dime pretty and having a bunch of computers telling my brakes what they should do is not my idea of bike control.
With the bmw there is never really a sense of the amount of braking pressure that is going into the rotors. mainly due to how much tubing and pumps are between your fingers and your pads. On the Ducati that's the complete opposite. She only had one rotor (less rotating mass) & a master cylinder with an adjustable piston ratio (allows me to tune how much braking/feel I get from the front). I can bring that bikes front so close to it's max braking ability that you ca hear the tire squealing.
If you grab your brake lever your probably going to bin the bike. Your suspension needs time to accept the load and your tire needs time to stay in contact with the road. They teach in the CA MSF class that as your front tire and suspension are loaded more you can brake more, on and on... until you come to a stop. If you just grab the lever your suspension will dive and greatly reduce front end grip.
Not to mention the ABS system on the BMW is HUGE! There are 2 large reservoirs for fluid under the tank, there are 2 good sized pumps next to them. In addition the whole system is controlled through the ECU.
Not saying that an smaller more compact system could not be build but really don't think it would be worth the time of effort. Not to mention the liability involved in making a product that was able to tell the brakes on a persons bike when to work and when not to.