First, nothing wrong with criticism. Second, I don't think we were having constructive conversation, acknowledging a story still can be good, it's just leaving a lot to be desired when a majority of content seems to fall into simple template using to pump out product. A lot of the stories imply that they ARE interested in doing it by the framework, but the details are glossed over; putting the cart before the horse.
You said yourself; people are into different themes, yet you feel the need to call it out? It's literally a forum to discuss our likes and dislikes, evoke discussion, and be okay.
Your LOTR example, IMO, is a poor strawman and misses the point.
If the goal is to compromise story for the sake of capturing an audience, then I think creators doing so deserve every bit of criticism they get lol. Transformation and shortcuts unfortunately don't go hand in hand when you aren't using a method that lends itself to supernatural, advanced technology, or bodyswap of some kind.
I'm not saying there's no room for criticism, I'm saying it's odd to criticise a story for being B when it's not trying to be B but it's trying to be C. Whether C fits in your (or anyone's) preferences is a different story, but that's what the LOTR example is about.
I personally prefer slower transformations, but to base a story that chooses to have a fast physical transformation on its lack of a slow transformation isn't judging the story on its merits; it's instead judging a story on your own preferences. That's not a fair criticism of an individual story, that's my point.
If you want a PG-13 rated Star Wars with a classic good vs evil that's suitable for children there's Star Wars. If you want an R-Rated Star Wars there's Rebel Moon. But to say Star Wars sucks because it's not gory enough isn't judging Star Wars for being Star Wars; it's judging it on something it's not trying to be.
Maybe I'm being unfairly broad, but I do think that "sweet/sentimental" works are prone to having pacing issues within the story they're trying to tell. It's not because they're not erotic enough, but rather that they often end up as a list of what the author is day dreaming about, rather than a story that's playing out. So it's more like I am criticizing a fantasy writer who wants to do something as epic as Lord of the Rings, but the writer has hyperfixated on how each battle plays out and just gives me details on the tactics and "epic" moments of each battle. But I'm not getting any characterization, story arcs, political considerations, etc. Or if someone is writing a superhero story, and I'm just getting their costume design and what their powers are and maybe a list of their rogues gallery.
If the story's intent is a romance, then there really should be enough characterization for both parties so that the story is... well, romantic. So that you're invested and feel fulfilled to see the couple end up together. A sweet and sentimental story that has the protagonist initially unwilling but embraces the transformation over time, should still have proper pacing showing us how that change in opinion occurs over the course of the story.
I didn't word this as clearly as I intended, but I have no issues with shortcuts or fast transformations so long as the story is paced sensibly relative to that transformation type and themes of the story. Going back to Gears, that's why I was criticizing the addition of the prosthetic to the story. The problem isn't that it's a fast/easy solution. It's that it's introduced as if to add to the feminization, but prior chapters already had Millie femmed to such a degree that if I shuffled chapters 6-11 around, you might not even spot that something was wrong. It begs the question, why not introduce the prosthetic right from the getgo? Heck, the cover story is already that Millie is trans... so if the medical science in the setting is that advanced, then why not get to that from the start?
Generally, this goes back to something I think is fundamental to any work of fiction: There's nothing wrong with having having a story or a piece of art be meant for ease of consumption. But if a work can stand up to scrutiny, it has that much more staying power. If the character motivations align with character actions, if the tone is appropriate, if the pacing of the story gives due attention to plot important developments, and if character's respond in ways that are consistant and give insight to who they are... Doing any of these correctly can only help a story.
I'm not sure these transformation story authors are trying to write a novel, with possibly Melissa's Aphrodite's Mirror as an exemption. I think they're writing pulp stories in the same vein as The Shadow and Zorro. They're writing short stories. Pulp is amazing and was the biggest, most popular storytelling entertainment in the western world. Even today, there are still pulp characters like Elric of Melniboné who are immensely popular, including his ripped off version by that Polish author after which The Witcher became a popular character. And yes, Geralt of Rivia is a stolen character; a ripoff of Elric. Robert E Howard has become pretty much immortal due to his pulp characters, despite only living to the age of 30. New Conan books are still published 88 years after his death.
I'd say pulp also has staying power. And as a big fan of pulp and short stories I'm happy it does.
The transformation isn't apparently the main focus, it's merely a storytelling device to put a man out of place and see how he copes with a new reality. It's not my personal favourite kind of story, but if executed well it could be done well. Coping with a sudden transformation can also be interesting enough to see without the growing pains of healing from surgery that would only deviate from the essence of the story.
I personally prefer a story like CBlack's Hotel Mystique, where the main character undergoes several slow transformations, but that's much more part of that story. Gears is different. I think Gears would work better if the story so far wouldn't have happened in, what, a month's time? KK wrote Medical Miss-Practice (published by Joe Six-Pack) and that story did the physical transformation on the first few pages and instead focused on how the main character would cope with the changes and as such is a pretty good comparison to Gears. KK has several time jumps to account for the mental changes the transformed main character undergoes. It's a small storytelling device that I feel works much better for such a story.
When someone's reciting the alphabet and starts with A, B, C we assume that person continued on for a while when we leave the room and return to that person going K, L, M and as we zone out and finally hear X, Y, Z. We don't need to hear all letters in between to assume the person did indeed say all letters in the right order.
In this example I understand your criticism is a person says A and two frames later the person said the Z, with all letters in between having to be assumed to be told by the reader. The story would work better if we'd get a E, F, G to at least have the author work on that sequence too. I hope you follow me in this example.
But I get that criticism. I don't think it's a problem with the sweet/sentimental subsection of the transformation genre though. I think it's a problem with amateur writers trying their best. Consequently, the forced genre doesn't automatically get rid of that issue. KK is an experienced author who's written many transformation stories. Some work better than others.