I've heard that in the book it's different but in the movie Will Darnell is Arnie's only ally when it come to Christine. Maybe Darnell didn't play much of a role in the relationship between Christine and Arnie but he didn't deserve to die for it.
shareI agree. Darnell may have been crude and obnoxious, but he was good to Arnie.
As another posted said back on IMDB, he was also a veritable font of one liners. Here's one of my favorites:
"That's the last time you run that mechanical asshole in here without an exhaust hose."
On second thought, maybe that's what Christine had against Darnell.