Are we missing the big picture on relief of suffering?

The tsunami that hit southern Asia recently has caused an enormous outpouring of aid, as it should. My question is, "what makes on disaster worthy of world aid and another unworthy?"
Numbers alone cannot be the determining factor. If such were the case, Cambodia during the time of the Killing Fields would certainly be right up there, but the West was largely unconcerned while 1.2 million Cambodians were systematically murdered. I have walked the Killing Fields and seen bones and clothing sticking out of the ground and wondered, "was this done in secret that it was allowed to continue for so long?"
Bangladesh, which suffered devastating losses during this recent disaster, has killing floods every year. We grow numb and unfeeling for the Bangladeshis because they are always being drowned." What else is new?" we ask.
Certainly the slaughter of hundreds of thousands in Rwanda was not worthy, nor is the ongoing slaughter of tens of thousands in Dharfour worthy of help. Somalia was worthy of a little aid until President Clinton got cold feet and did not adequately support the military who were delivering the aid.
Here is my thinking. If God causes the suffering (such as the tsunami), we provide aid and some aging rock star writes a warm and fuzzy song about our common humanity which makes millions for charity and also revives his career. If man causes the suffering, then you're on your own: you don't get a song, you don't get a C-130 full of rice; you get bupkiss! I think the West is bored with warfare and the resultant suffering. We cannot get our minds around the universality of "man's inhumanity to man." Such constant wars and suffering are a constant reminder to us of our fallen state: we do not know peace! Helping out refugees caught up in a war only reminds us of how constant our evil remains and how hardwired its causes are in our lives.
Perhaps the disasters that receive the world's outpouring of aid are those which are media friendly or occur during a slow news week.
There must be a psychology behind which disaster receives help and which is ignored or given only a kiss and a promise, but I surely am unclear of the principal behind it.