I agree with Mani kv, however the full answer was hidden in Mercedes S-Class that has already got the Active Break Assist. Video can be seen here.
ABA vs Human (source)
Most drivers, under normal braking conditions as well as under emergency conditions, start out with little brake pressure and whenever necessary they will increase their pedal effort. In an emergency this behavior leads many times to a crash since the car could not be stopped in time. Those situations require maximum pedal pressure from the beginning - if necessary the effort can be reduced later in the process.
I addition to that, I forgot to consider the reaction ability.
A controlled study in 2000 (IEA2000_ABS51.pdf) found average driver reaction brake time to be 2.3 seconds.
After reading this study I think there is no doubt that dropping speed automatically is a win-win. In addition to that it can always be switched off in case, where driver wants to act "bad boy".