Enzo, I disagree. If you don't shock people, if you fail to convince them that it is absolutely, flat-out, downright dangerous to open their doors without looking then they don't take it seriously. When I was doored (filtering between cars, shame on me) I actually heard a pedestrian laugh.
Have you seen Mayor V's PSA for the "Give me 3" campaign?
http://www.youtube.com/watch?v=hnLViXcG7mEIt's utterly dull, wishy-washy to the extreme, and instantly forgettable. I really like the Transport for London ad:
http://youtu.be/64T319-PhDIIs it uncomfortable to watch that cyclist hit the car? Yeah. I cringe every time I see it. But if temporarily upsetting people with the image of a cyclist getting hit by a car is what it takes for the ad, and therefore the lesson, to be memorable then that's fine by me.