I discussed that whole "everything happens for a reason" bullshit in a blog of mine as well if you'd care to read:

http://www.thoughts.com/MisterSelfDestruct/blog/383 157/

Minus that whole space between the three and the one.

Hatred happens for a reason so do all the others they may serve no apparent purpose but there's a reason for each one. Something happened to make a racist or a rabid PETA protester a reason they are who they are and it may be the reason they do what they do and therefore the reason someone had to die it became unavoidable at some point. It maybe that your parent/spouse/child perishing from a given rare cancer serves no purpose that you may ever realize but the relevant gene being in your family genome might inspire one of your progeny to find therapy or a cure for it. The death of a fine kind and nurturing woman may seem pointless but we don't know that she wouldn't have died a much worse death the next time her number came up. We can't know the universal scope simply because we are too limited to ponder all of the universe at once seeing infinitely in all directions and all times all at once. Whether it's Scientific laws or God's will there are driving forces that do predetermine certain events factored against chaos&avoidability/freewill & you get reasoned probability. The greater good as a supposed outcome is what I suspect is the inference that piques your ire & we'll just never know that so getting angry does no good it's like getting pissed you can't pick a winning lottery number if buying lottery tickets makes you happy... have fun, if it pisses you off then don't but why stop that guy from having their fun because you don't understand it (Excluding addicts who can't provide for themselves thus needing help to stop).
The simple fact is that what has happened has happened and not accepting that won't change the fact that it did occur it may allow one to spin it to a more palatable version of what occurred but, it won't change the past only cloud the judgment of those studying it in the future so accepting what's happened is the only sane thing to do. You get angry when people use a phrase which conveys a belief; you should remember that as recently as tomorrow in some parts of the world you could be executed for your beliefs. A little tolerance goes a long way.