What is disproportionate about it? Large bombs don't go off in US cities every day. Are you surprised that there are bombings in Iraq? Is that something you don't expect?
When has the news ever covered stories solely in proportion to the number of people who died? I don't understand how you could be astonished by this...
Well, when I was reading it on HN I thought "There was a bomb in Boston and two people died, what's so intersting about this, why it's on HN and why are people in the comments so emotional?" I'm not from the US but even where I live this is top news. I felt similarly with the boring and overhyped Fukushima crisis.
Why wouldn't you? HN is hosted in the US. It's going to have US news occasionally. The bombing only killed 3 people because of all of the first responders. It could have easily been in the double-digits. There are 150 people injured by the blasts.
... And none about chemical weapon's first use in Siria "yesterday" with a lot of innocent people running with burned flesh in the streets, yes I can understand what you are trying to say. Sad times.
I'm understand also, as you should, that this is an international community of people. There is, probably, a lot of brilliant minds here from many coins of this small floating rock, so it is expected that we could talk freely about universal problems and achieve much more than just a local and restricted point of view (and maybe to talk about possible ways to avoid this tragedies again and again).
What is disproportionate about it? Large bombs don't go off in US cities every day. Are you surprised that there are bombings in Iraq? Is that something you don't expect?