Why separate brakes/brakes at the front and back?

Why is there actually (still) two independent brake circuits for front and rear brakes on the motorcycle? Wouldn’t a system with automatic, load-dependent braking power distribution be realized on the motorcycle, which can be operated via only one brake lever or pedal? I mean with modern cars with current “drive aids” the electronics even specifically intervene on the brake of individual wheels and as a driver I only have to pedal.