I do think it's a beautiful thing when an author is clearly going for a metaphor, but the diegesis gets in the way. The story has symbols, but they're not just symbols, they're real things that exist within the world of that story, and as soon as the reader thinks about this, the symbol can be shattered.
I don't know what it is I find nice about this, but maybe it's the wet impact of meaning-making against base reality.
I was asked for examples, here are two:
X-men is always the one that comes to mind, where superpowers are a metaphor for being gay, or Jewish, or non-white, but on a diegetic level, superpowers include things like mind control and being bulletproof and blowing up things. So then you have mutant registration drawn as a parallel to the government making lists of undesirables, but what the writers have done is made imagined threat into literal threat, as the people with superpowers actually can effortlessly murder someone. That is, the false rhetoric of destruction has become literalized.
There are mecha shows where piloting the mecha is a metaphor for the overwhelming burdens placed on children, but diegetically it actually is the fate of the world, and so this might be seen to justify things that are completely unjustified. If failing a test is literally going to result in hundreds of people dying, then the cruel authority figures are making uncomfortable triage decisions by putting enormous pressure on the cadets. And if, in the metaphor, the parents need to come to the realization that their children should be allowed to live their own lives ... we can kind of see how that doesn't work if the end result is that a kaiju stomps the country flat.
I swear I read a book that was supposed to be pro-gay that treated its gayness metaphor as a contagious, curable disease. Also, being gay meant you could regenerate from any injury and it felt really good, so before the protagonist got infected, she nearly got killed by accidentally walking in on two gay teenagers blowing each other up with a grenade as a sex equivalent.
It's why, I think, in pretty much every story about aliens/robots/elves/mutants/etc, it's a mistake to read the aliens/robots/elves/mutants as a direct one-to-one metaphor where something said about the aliens/robots/elves/mutants is something said about gays/browns/disableds for anything. Because gay people don't come from space, and disabled people can't shoot lasers, and if you were to imply that one were the same as the other you would be wrong, because they are not the same.
But it's always gonna have similarities though, right? Humans react to groups-of-people-that-are-not-like-them in semi-predictable ways, not always the same way, but there are commonalities. It's kind of inevietable that if you had aliens/robots/elves/mutants in your story then people would react to them in a kind of a way, and that way would *rhyme* with the way they react to existent types of people, especially if you want to be remotely interesting about it, even just on an individual psychological emotional level.
And that inevietabiltiy is something that makes it almost like... not worth criticising. Obviously if you interpret the orcs from mordor as a one-to-one substitution of Canadian people then Lord of the Rings would be a horrifically Canuckphobic piece of media, but you really don't *have* to interpret them as a one-to-one substitution!
There's a bad tendency in a lot of lefty media crit to act as though stories about aliens, robots, elves and mutants *aren't* about aliens, robots, elves and mutants, as if that's always just a thin and unimportant veneer laid over stories about real life social issues for a bit of flavour.
But no! Stories about aliens, robots, elves and mutants REALLY ARE about aliens robots elves and mutants! These people care about aliens robots elves and mutants and really do want to write about them!
I think in general there is a tendency by many critics to act as if a speculative fiction story cannot be reduced to mere allegory, it is of no value, because they are fundamentally not very interested in speculative fiction. But applicability is not the same as allegory, and the former is often more interesting (and has more to say).
