Ok, you start talking like that and you lose any political power you might have had. You might be able to incite a few other like minded people into your 'revolution' but most people will look at you, and just say this is why pot needs to be illegal, look what it did to this kid, he is now just a senseless ranting idiot that is unable to form a strong argument. However if you come to the plate with a strong well laid out argument on why is should be legalized, you might be able to get many more people to side with you, and hopefully some that actually vote. Now you have legal power. The people of your state/district, control who gets elected from that state to congress. If you can get a large portion of your representative's constituency to write to him/her saying that they would like to see the legalization of weed. It is in the best interest of a congressman to vote to the favor of his/her constituency. If they don't they lose there jobs. Diplomacy does work. Spewing randoms out of a megaphone does not.
And yes martyrs are also great ways to bring attention to something. However a kid shooting up a station only provides martyrs for the side against the kid. What that incident says is if we let people use weed this is what there kids will end up like.
So in case you were wondering why weed has not been legalized yet try and actually think about these ideas, People have tried senseless verbal abuse on the laws and lawmakers, these actions tend not to get results.
Back to Police Brutality, This incident lends enormous emotional force behind imposing legal restrictions on police, and or better selection process of deciding whom becomes a police officer. It has created a martyr. This person who was killed in Vancouver becomes a rallying point for many enraged people. It lends emotions to the argument against police brutality. Not only will it serve as a rallying point but also provides strong evidence of the need for change. Now someone or a group of people can approach, the RCMP and say "look, unless there are radical changes in the training and selection of police officers as well as in the disciplining of officers who step over the line, we will see more incidents similar to this one." Now the RCMP will start to listen to this, they have to unless they want a city the size of Vancouver enraged at them. Believe me, an enraged, public is the last thing they a police force will want on there hands. However, you will not get the vast majority of the public up in arms against the police just by yelling "Fuck the Police" as much as you can. maybe a small minority, but not enough.