As a motorcyclist I also want to give my input.
I commute everyday between Centurion and Midrand.
I do not speed and only when cars go less than 80km/h do I even concider lanesplitting and try to not go more than 20km/h faster than the cars.
I have also never broken a cars mirror because I felt that they were being retards.
What does happen more often than not is a car jumping from one lane to the next without indicating or barely indicating.
This is dangerous for bikes as well as cars.
Indicators are supposed to be used to indicate your intentions not your actions.
That is all.
I fully agree with you that the motorist should indicate. But I am talking about a cpl of personal encounters I've had. Where the guy comes screaming along the line inbetween the cars and then you just see him at the last second before you change lanes. I know not all bikers do this, but a lot of them do. If you are stuck in traffic you cannot always see 3 cars behind you and you might miss the biker coming down the middle. That'a all I'm trying to get at. They should also "Think Car" and not always expect that we can see them or hear them for that matter... You might also have a loud pipe on your car, or a loud stereo... So yeah