When NPCs are regularly used and then die, it's easier. However, it's hard to keep track of a catalog of NPCs. Some people will reference specific ones on the regular (like me with Pitbull on BSG:U), but it's pretty much 'old hat' for an ST to whip out some NPCs special use for a scene to kill them off.
And it's hard to dredge up those fucks to give. I try. I find it easier to slip into those other mindsets (but then, as an author, it's why I RP; to explore other character types, upbringings, etc. to help my writing). But when I'm writing a screenplay or novel, I know the deaths coming, I can weave in the characters involved, it's not just...
'Anderson died and plz remember you knew him for the past year!'