Against
- Presents a bad image of the Stack site from broken images & dead links, especially considering what Stack Overflow is all about.
- It being there sends an unclear message of what content the site actually allows.
- While the close message is quite clear, it's not necessarily going
to be read, or even noticed as a visitor may be linked to one of the
many answers beyond the close reason.
- Maintaining these questions will be futile as replacing broken
images, links, etc will be an indefinite maintenance task as links
continue to break (including fixed ones).
- There is no real place for these questions, and the site structure
and community modding cannot manage them.
For
- It's a huge post and so many potential keywords and images to bring incoming visitors. People finding this from Google or other sites may eventually "wander" to other parts of Stack Exchange and sign up/participate.
- It is a bit of fun. While Stack doesn't promote this, a little bit especially "from the past" is cheery and shows the owners/mods/staff etc are not stuffy*.
- They're usually from a time when it was allowed (a bit more).
- They're a bit of fun (I know I mentioned this one, but I thought
that it was such a big one that it was worth mentioning twice).
. * I didn't say they're stuffy, but there are plenty of sites and blogs slating Stack for "their hard edged ways", and fun and quirky questions being allowed to remain shows that where normal play is resumed, staff/mods are simply pushing to provide a decent and strict Q&A site, and not stuffy at all.
Problem
The points against are valid and quite detrimental to certain key aspects of Stack, however the points for are also quite valid.
So it certainly needs addressing, not leaving, although certainly not just "nuking" (especially with the potential of inbound traffic).
Suggestion
Malachi's suggestion was a good thought and would be perfect - to have a historical place for these things - but this is likely way to much dev time for what would be a few of these historical questions.
Ideally you'd have a message with fixed positioning so whatever part of the (usually huge) question the visitor hits they would see the message, however this is of course a fair bit of dev time again.
Something like:
This sort of content is no longer allowed to be posted at Stack Overflow! This question has only been allowed to remain for historical reasons and because it's gathered so much attention, and would normally be closed rapidly as "off topic". It is also not part of our maintenance system and so some links may be broken or answers not particularly useful (or funny).
Anyone reading it can see clearly it's not allowed, staff aren't stuffy as have left it in place, it's known there are broken links or other issues (so Stack don't look like amateurs etc) and all the above mentioned "for" reasons remain intact.
The same message could also be quickly applied to any other "historical" question which has the same issues of being off topic and sending out the wrong message, etc.