In addition to this, if you write a story with a character who is gender fluid/non-binary, how does it get tagged? Gender bender works for this even without any fetishization of a specific form. My story is about a rock, something universally agreed upon as being genderless. Drawing from Chinese mythology, my rock "gives birth" to a monkey and gets influenced by humanity to "adopt" a gender at different times.
Don't mistake the fetish stories of authors who just want to see boobs with those made by trans authors who just write characters (who, yes ultimately get gender bent). Also, don't write off a genre because of this same reason. You can find some real gems if you just consider the premise of the story and look at the tags beyond "gender bender".
I'm just going by the definition here. Autogynophilia is categorized as a fetish, although I'd say it's a little more complicated than that and has a very non-sexual aspect to it. Some guys just have fun with the idea of viewing themselves as female in a non-sexual way I'm sure, and some women likely have the same experience in terms of autoandrophilia.
The point is that it's officially categorized as a fetish. Also, as I mentioned later, I am very much of the opinion that the absolute best MTF genderbender stories are written by women and are not explicitly sexual in nature. (Or at the very least don't overly emphasize the sexual aspect.) I mean, I'm perfectly sure men are capable of writing good non-sexualized genderbenders as well, it's just that I've seen a pattern where the majority of the good ones are written by women.
EDIT: I might also add, with the subject of transgender having come up, I am also of the experience that genderbender also tends to not be written so well when the writer is trans... or at least, it's pretty bad when it's written in a way you can clearly tell the author is trans. They generally are trying too hard to push some kind of agenda and it ruins the actual story itself... and ironically it also ruins any kind of exploration of gender roles as well. I'm not even really sure they do a good job of getting across the trans experience, but I'm not really sure I can talk on that exactly.
I mean, once again, I'm sure there's some reasonably skilled trans authors out there who can do a good job with it, but they probably make up the same % of the trans population as there are good authors among the cys population. In other words, really not many at all, and therefore if I ever have seen a good one written by a trans author then chances are I wasn't aware the author was trans. That said, with how vanishingly small a % of the population they'd have to belong to (the intersection of two already incredibly small populations, which then has to decide to write in the gender bender genre, cutting the population down again by AT LEAST half (and I'm only putting it as high as half because I am making the likely unfounded assumption transgender authors would have a stronger draw toward writing in this genre,)) I doubt I've actually seen it, even without knowing.