WARNING: THERE BE SPOILERS AHEAD FOR FRIGHT NIGHT!!!
I recently saw Fright Night with some friends about a week ago, and I liked it. But the entire time I was watching it, I ended up analyzing it because that's what a slightly bored English major does. I could talk about how the movie is a man's movie about men and how the women don't really play a role in it aside from being objects of desire and objects to save, but that'd be boring. So I'm going to talk about why Ed had to die.
To begin though, we need to look at Charley, the film's hero. Charley is a beta male who pretends to be an alpha male so he'll be cool and get a hot girlfriend, and by the end, he becomes a true alpha by killing Jerry and stopping the vampire apocalypse. Charley, for most of the movie, is in a transitional stage, and you could argue that the entire movie is a sort of bildungsroman for him, where the rite of passage is destroying Jerry and his covenant. Charley doesn't quite know himself yet. He knows he wants the sexy Amy to like him (and to sleep with him, which of course goes awry when she tries to initiate it because Charley isn't quite an alpha yet at that point), and he knows he doesn't want his geek past to haunt him, so he sets out to be cool and not associated with anything that he once enjoyed.
This means getting rid of Ed because Ed is a tie to his beta, geek past.
Ed is a complete beta, with no hope of redemption. He is short, awkward, wears glasses (why am I describing myself?), and he doesn't mature in the little bit of time that we see him in the film. In fact, when we first meet him, he blackmails Charley into investigating the recently disappeared Adam's house so to prove that Jerry is a vampire. Ed also purposely embarrasses Charley in front of the 'cool guys' Charley hangs out with in order to force Charley's hand. There's no maturity in this action. It is the action of a petulant child who wants his way and his way only.
And this is why Ed had to die.
No one else who had been bitten by Jerry died, except for Adam's parents who are irrelevant as most parents are in this film, the stripper (woman to be saved/desired), and Ed. Not even Peter Vincent, the alcoholic, rude, and womanizing stage magician dies, even though his character is fairly irredeemable in itself.
So why did Ed have to die?
Because we needed Charley to become an alpha male. And because Peter Vincent can be seen as a stand in father figure for Charley. Ed is his one remaining tie to that old life, that one thing still holding him back, and for Charley to become an alpha strong enough to confront Jerry and kill him, Ed needs to be destroyed first. So Charley kills Ed and becomes strong enough to fight. I could go into how the stake to the heart is some sort of phallic symbol and open a whole other can of worms, but I get the feeling I'm digressing. Maybe another essay is in order.
It's interesting because the cool guys, who are turned at some point in the film, are turned back to humans by the magic cross of movie magic. Ed is really the only friend-vampire who is killed. Even though he was the first person to realize that Jerry is a vampire, Ed still must die in order to give Charley the chance to become an alpha male, which pushes the plot forward and allows for the nookie to happen at the end. My evidence? Charley can't sleep with Amy until the end of the movie, which is in part related to his obsession with Jerry and in part because Charley is still beta at that point and horribly nervous about his first sexual encounter. He actually looks for an excuse to pull away from her, and Jerry's existence is that excuse. Once Charley gains the strength to kill Ed and therefore the strength to destroy Jerry, he has the strength to have sex because he is now the alpha and in control.
Weird? Yes. But it does make some sense, right? Probably not. I'm slightly overworked and my brain thinks this is a good idea.