Re-watched last night and agree this movie belongs in The Canon. One thing that struck me that I hadn't noticed before (I was 15) is that John Doe created this fake image of himself to be immortalized. The murders, the room, everything was constructed by him. He didn't even set out envying Brad Pitt. His plan would have been used on any detective that would have come along investigating the case. Don't have a pregnant wife? Have a son? A daughter? A parent? A friend? It could have been anybody's head in that box. Wrath was going to happen in response to his faux-envy.
Coincidentally I happened to be watching The Simpsons and they parodied that cop's last day on the job thing back in 1991. https://www.youtube.com/watch?v=MOk4hQXbGDs