You're thinking of time and money costs; those are just a small part. What about the costs of being reminded of such a terrible thing every time you hit a 404? And what about those costs for people who lost their child five or ten years ago, and for whom those are just terrible memories, with no hope left?
All great points. I'm reminded of that whenever I see one of those "cleft palate" pictures. It's a terrible thing of course, but it's not exactly something that lifts your spirits and should not be forced upon people.
You make an interesting point. I could see how these 404s could be in poor taste depending on the tone of the site, but I'm not really moved by the "someone might feel bad about something they saw on the internet" argument.
