Why don't newly-designed sites get custom 404, 500, or captcha images anymore?

Question

By "error images" below, I mean the images used on each site for the 404 Not Found page, the 500 server error page, and the captcha page. I'll admit that I'm a bit biased as I strongly believe that each site should have its own, unique set of error images, as they add a certain level of charm to the site's designs, which I don't want disappearing.

Back when the sites were being redesigned last year, the original plan was to unify these error images across the network. In response, I had requested that the team consider allowing sites to continue having their own, unique error images, and that request seems to have been granted: all of the existing designed sites got to keep their site-specific error images.

However, I later found that the Code Golf site, a site that received its design after the new design layouts were adopted, didn't receive custom error images. When it received its design, there were no custom images where they were supposed to be, resulting in those image URLs serving 404s themselves. Later on, staff changed the pages to force-load the images for beta and non-designed sites.

After some further searching, I found that none of the sites that went from being non-designed to designed after the responsive design layout changes received customized error images, which have historically been deployed when a site proceeds to the "designed" phase. Anime & Manga, one such site, was told the following regarding this:

404, error, and captcha custom designs are out of scope for new designs, I'm afraid.

Why don't newly-designed sites get custom error pages anymore? Is it because of a lack of designers?

And if the plan is to not design custom error pages for sites anymore, will community submissions of custom error images still be accepted?

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(Side note: while Stack Overflow did lose its "polyglot" 404 image, that is irrelevant to this question, as it still otherwise has a site-specific set of error images. That was just the custom images changing on one site, and not a reflection of what happened network-wide.)

Answer 1

It seems that some of the most recently-designed sites are getting custom 404 pages. They're not the comical or memetic images from around the internet like they used to be, though. They appear to be designed entirely by Stack Exchange staff designers.

From the most recent blog post about "Themes", there are new error page icons for the most recently-designed sites. My personal favorites are the Data Science images (from this draft post on DataScience.Meta.SE):

In order, those are the 404, captcha, and error page images.

The introduction of these drafts (for the themes are currently drafts, and are not currently implemented on the related sites yet) raises a few questions. Firstly, are old sites that have had their 404 pages removed going to get them back? Additionally, one of the stated reasons that custom 404 images were removed is that they did not have reliable translation to dark mode. Are these newly-designed sites slated to have dark mode added, and if so, are these new images going to be compatible with dark mode? These are probably out of the scope of this answer, but they're still in the back of my mind.

Overall, though, it seems that site designs are reintroducing custom 404 and other error page images, this time entirely designed by SE staff.