"And I'm not seeing what's so "dishonest" about the practice.
You are using fiction to support an argument. And since it is your
fiction for your
argument, it will be tailor made to support your points, while reality may not support your points.
"So you wouldn't say an anvil of tolerance towards all races/sexualities shouldn't be dropped in kids TV?
Is that an anvil? Does it thus fall under the statement "No anvils should ever be dropped in fiction"?
"Also good luck swaying a younger audience towards your argument with pamphlets and studies.
If they are too young to be capable of intelligently approaching a subject, then why bother discussing it with them in the first place? Further, if they are too young to actually grasp the situation, then any and all methods you use to convince them cannot be based on logical argument.
"I wouldn't say it is dishonest, in the fact that the world can be created differently can be used to show views in ways that would be hard in a plain text essay, and with a story framing it make it easier to understand.
There is nothing stopping one from using hypothetical scenarios in an argument. The important thing is that it is openly presented as an argument, and has real evidence as well, instead of just hypotheticals tailor-made to support the argument.