It would be instructive if more people took motorcycle safety training. They really emphasized that you should ride as though there could be a dropped load of concrete, boulder, or pothole around every corner, every blind hill, or every car, and stop accordingly.
I think this is mostly because the consequence of hitting debris is much more likely to be fatal on a motorcycle, but it would be good advice for anyone, really.
Second, a huge part of safely operating any vehicle in an environment (especially a chaotic one you share with cars, bikes, and pedestrians) is awareness of your surroundings and the ability to avoid collisions. This is seriously driving / biking 101.
If you are zooming around on your bike and just thinking "hope no objects / people / cars are sitting stationary in my way because there's no way I can stop and I'll definitely hit them", then you're a dangerous menace.
I agree with the arguments about moving cars pulling into the bike lane, doors opening, etc, BUT if you can't avoid smashing your bike into a parked car with enough force to go through the rear window, then you definitely aren't skilled or responsible enough to be riding in the city.