I think (particularly if you're neurotypical yourself) you should probably think really hard about what you're actually saying when you compare autistic people to robots, and whether that's an accurate or charitable description, or about what it would mean to actually live with that stereotype.
I fear you miss my point. I'm not saying that robots are an accurate depiction of neurodivergent people, I'm saying that the common depiction of robots (struggling with social interaction, recognizing and contextualizing emotion, etc) hews close enough that people start noticing parallels, particularly with Asperger's (or at least the common understanding thereof). Frankly, accuracy is irrelevant; it's coding whether it tracks to reality or to stereotype. Hell, for the most part the coding of this particular example isn't even intentional.
Point of fact, it's not uncommon to see the specifics of the coding applied to a given narrative criticized as
contemptible for how it reflects a lack of research or understanding on the author's part. Eg, Detroit: Become Human was blasted for its hamfisted and tone-deaf attempts to paint the robotic characters as basically Civil Rights era African Americans.
Hell, to your point, this manner of writing robotic characters has been getting increasing flack specifically because the near ubiquitousness of the pattern (and the fact that representation of those demographics outside of such characters is in the range of slim-to-none) carries prejudicial undertones that neurodivergent (and asexual/aromantic) people are somehow less human or 'incomplete' as people. I didn't invoke robots as giving such demographics fair representation - because it certainly doesn't - but rather I invoked that convention specifically because it showed how coding can carry negative implications if the writer isn't careful. And in that particular case, a lot of writers aren't careful.
This in turn ties back to my original point. And respectfully, I feel it's worth reemphasizing, as it reads like you're still treating coding as a form of fanservice, something intended to hook a given demographic audience ("aimed at particular groups" and "appeal is an important part [of coding]" as you put it). While yes, coding
can result in the evoked demographic liking it, the operative word is "can". Coding is completely independent of targeting. That something is written in a way that is evocative of a situation or demographic does not imply that those people are a target demographic for the work. Point of fact, one of the more common bits of coding (due in no small part to the influence of the dumpster fire that was the Hays Code) is giving villainous characters [stereotypically] queer attitudes and mannerisms specifically to help paint those characters as somehow 'wrong' or incompatible with society due to those traits historically being perceived as socially unacceptable. The social implications of that are
absolutely terrible, to say the least, but the terribleness is mitigated somewhat by the ironic fact that such characters often end up being just plain fun and more interesting (and therefore often more popular) than the protagonists (Eg. most Disney animated villains).
Another bit of coding that probably surpasses that in terms of commonness is actually the use of accents to evoke personality traits (stereotypes, really) through association. To use some easy examples, if you watched Yugioh as a kid, you probably remember that several of the characters had strong accents for that very reason. Bakura - who consistently spoke very formally in Japanese - was given a British accent to convey that he was formal and polite, whereas the very informal Joey (Jonouchi) was given a Brooklyn accent to make him sound more like a rude loudmouth. That's not fair to Brits and certainly not fair to Brooklynites, but it's an association that's relatively intuitive to the general audience.
My Fair Lady similarly is built on the idea, with the lower classes using strong Cockney accents, and Eliza being trained to speak with a 'proper' British accent with the explicit purpose of convincing people that she was instead a member of the upper classes based
entirely on how she spoke (ultimately resulting in a linguist mistakenly deducing that she was in fact Hungarian
Royalty). Want the kicker? We use the exact same accents to convey the exact same thing in Les Miserables...where the characters are
French and have no business speaking in any kind of British accent. While it can be handwaved as a practical use of accents in My Fair Lady, in Les Mis it's rather blatantly done purely to convey the social associations we assigned to those accents. Similarly, if you look at the character guidelines for the play Lysistrata (by Aristophanes), you're probably going to notice that it suggests Lampito should have a thick accent (Usually Scottish in England and either Appalachian or Texan in the States) to convey a meaning to modern audiences that roughly approximated the Spartan stereotype that Arisophenes was making use of.
The corollary of this, of course, is that just as something being coded to a demographic doesn't mean it will be flattering or appealing to that demographic, neither does something being appealing to a group in any way indicate that it was coded to that group. To use an easy example, Draco Malfoy was incredibly popular with lady fans, but he is certainly not coded as a lady. As we went over, coding is about
perceived parallels and he's not evocative of anything in particular, least of all the demographic that started fawning over him after Tom Felton started portraying him in the films (no seriously, there's a marked difference in the character's popularity coinciding with the release of the films).
Heck, for that matter, coding doesn't even necessarily track to a demographic. The Kaiju of Pacific Rim, for instance, are coded as
Climate Change and the catastrophic ecological changes (such as more dangerous hurricanes and functionally poisoned oceans) that result from it. It's not for nothing that the giant robots are described as "giving you the strength to fight a hurricane and win" and then get thrown up against giant threats (that were becoming both larger and more frequent) coming from the ocean, that we then give cutesy nicknames and rank on a 1-5 Categorization system, and which giant seawalls failed to meaningfully impair (Remember, it's a Guillermo del Toro movie. His philosophy is that - and I quote - "monsters are living, breathing metaphors"). And going back to the OG kaiju, Godzilla was the terror of the bomb and specifically the dangers of our continued testing and development of such weapons, with the opening scenes in particular making very unsubtle reference to the Bikini Atoll disaster.
Point being that there is neither a positive or negative correlation between appeal and coding; it can easily go either way. Depending on the specifics it can be very welcome, very offensive, or anything in between. It's very much a case-by-case basis, and that's part of what makes this such a complicated subject. There's no clean 'this is good' or 'this is bad' about it, nor is it something tied to even a general authorial intent. Never mind that the associations an audience makes are not always intentional on the writer's part.
And I apologize for talking your ear off about this, but literature and the analysis thereof is kinda a passion of mine.