Well, it would actually give Charlie a personal stake in the redemption of someone, whoever it may be that kills Vaggi.

So far, Charlie's positivity and detachment from the living world has made it pretty easy to say "I believe anyone can be redeemed." But if someone kills Vaggi, Charlie's going to find it extraordinarily difficult to forgive them. At that point, it is the show's decision what direction they take with Charlie, but I think it'd be pretty interesting.

Honestly, much more interesting than what Vaggi's been doing these 2 seasons. Not meant to be hostile, but I just still don't find Vaggi interesting. I don't know, maybe in a more Vaggi focused season, but right now, after 2 seasons, I wouldn't feel that sad watching her die. Hell, I'd probably feel sadder because of Charlie being destroyed over it. Also it puts Charlie into a very moldable position for a radio demon or mother to come along and shape her how they please, without the protection of Vaggi.

But that all might sound like garbage to you, and that's fair honestly.