Interesting post over by Jim Smith over at Mightygodking.com yesterday. It got me thinking, as one does, about the writer's 'tool-kit'-the storytelling tropes that a writer uses to tell a given story. Every writer uses these tropes, though most employ them differently depending on the story and their particular style of writing, as well as on any cultural/religious/economic/political/gender/etc. biases they might possess (or wish to explore). Basically, the tools are the same, what's different is in how you use them.
Death in comics, at least in the case of the Big Two, has never, IMO, been an 'event' in and of itself; instead, it's simply another tool. Now you could argue that big-E 'events' are tools as well, and they are, though I'd argue that they belong in a whole other tool-kit, i.e. that of the promoter. But death, the death of a character...that's just another tool. In fact, it's a tool of transition. A way to shuffle the cast a bit and add to (or subtract from) the motivations of the remaining characters.
In the serial format the status quo is the starting point for any given story. The characters, by their nature, can't be changed permanently, but a short shake-up of the status quo is an effective plot device. It makes (one hopes) for an interesting story, and can be easily undone, resetting things back to their former state. Death in comics (or in any serial storytelling format, really...soap operas and comics have a lot in common) is a useful tool for inciting one of these shake-ups.
The problem is that death, like any tool, can be overused. When it becomes the standard, rather than the every-so-often, it only serve to weaken the effectiveness of the writer's tool-kit.