It's rather simple rules to be honest, but those rules rest on an extreme subjectivity, a desired vibe/goal. That subjectivity while isn't entirely random it does have bubbles of thought. Such that someone that gravitates towards a sort of skyrim vibe will have an entirely different idea of what is reasonable than a person who is more into Persona and more interestingly it isn't just bubbles as people are able to shift too depending on what they expect- like if I play Mario Party I'm not looking for Bloodborne vibes.
The simplicity is the story of the visuals. What are you trying to convey? Your simple viewing of what people have issues with can come from that. Some people do just have problems because of morality or stuff, but from what I read most people, at least my self particularly, they see mascot armor and think 'the story is you're making this out to be a joke'. And I like jokes but I don't like jokes right in the middle of content that was supposed to be serious.
Like people who think frog suits or bikini armor is reasonable might also think "wth?" if we had 100% full detailed nudity naked fighting or if you could wield tools that look suspiciously similar to what might be used in Saints Row. I don't feel unreasonable to suggest the amount of story telling bikini armor offers is limited in comparison to even slightly more armor, but even a bikini armor user who feels they've enough story from it might be like "naked isn't a story, I don't need to see the twirly whirly" lol.
Ultimately I would look at how unreasonable it is or is not by asking the artists that design characters and asking them to design the character. What I mean is of course we have things like chocolina, that sexy chocobo outfit girl, we have loads of silly moments, and thats great, imo, but the amount of times you're going to see them take that sort of outfit, as the main outfit, for the main character of the entire 'story' is going to be.. basically nil. SE was never going to put cloud in a frog suit as his standard combat outfit, they might do it shortly for the humor but they would do it for the whole purpose of the scene- they're not going to frog suit cloud in the middle of his epic showdown because the artist themselves would know how damaging that would be to the scene.
So you might have difficulty imagining immersion or realism for the perspective of someone else, and that's fine, I feel like honestly its like trying to imagine having or not having different types of religions or political beliefs- you have to shift your entire world view if you're trying to do it honestly when you don't match them in the first place; however, I think you can more consistently replicate how many people here feel just by imagining you're a professional making a professional game that MAY have some silly moments but also HAS to be taken seriously with high cinematic value in other points.
In this way I hope how you can see mascots and bikini stuff being potentially pure fire to the scene, taking an epic dialog with Gaius and turning it into a clown car show. As I hope you could see how in a professional setting the artist / designer of the game would be very unlikely to do something like that to their 'serious' scenes.
If it was your job to make the next FF game, you might frog suit him at a few points cause it'd be hilarious, but you'd not frog suit him for everything unless you were intentionally making the entire game a joke. With a clear note frog suit isn't meaning frog (like the frog from Chrono Trigger) I mean clear joke mascot outfit. And again I'm not annoyed the bikini or mascots exist, I think it's awesome they do, men in dresses is not an issue to me either, just wish there were some sort of FF filter wall between serious content and joke / another day in the city content.
Wish they had designed their glamour system more sincerely to allow as few restrictions as they can for player freedom without damaging the seriousness / professional artist approved vision of the game (to be fair my perspective on the system has shifted a lot from back then too, so.. I'm not begrudgingly saying it or anything, as I think now that a glamour system is a must in any non-hyper realistic MMO, but hopefully they can encourage a FF visual and maintain serious content as much as possible while not using too many rules). Of course we might want to tweak the example further now though, say seriousness in One Piece setting is worlds apart from seriousness in Divinity Original Sin- which gets us pretty much back into to the massively subjective world... lol.. but you hopefully at least could see how someone would love the style of FFX and not FFX-2. So while still super subjective again you might at least be able to equip different lenses of styles and see how certain lenses are just more or less interesting to people (like certain types of games, FPS, RPG, moba, etc).
So some people might want the art direction of FFX-2 here and others the FFX. Honestly fine with lulu direction in FFX (or tidus, his outfit is pretty wild too lol), and in general all of FFX, but I thought FFX-2's costumes were just 'too' silly and it didn't capture the vibe of FFX, the reason why I touched FFX-2, in a way that interested me as much as FFX did.
A FF filter in that a professional making a game would apply to ensure their game is viewed in the light they're looking for. While there is still some subjectivity of this compared to 'mah immersion' I hope you can truly feel the difference, an sRPG might allow players to make a joke out of their own game by optional costumes but it's not going to willingly do it on it's own unless that scene was meant to be a joke in and of itself (and jokes are not always bad, Cloud dress up was funny to me and I had good fun with that, but if I had to play Cloud in a mankini the whole game I'd be like '...this game doesn't take itself seriously').
The option to do that could be funny though, like in Assassins Creed I made the game a joke by keeping Bayek in his bath towel outfit because I wanted the game to have that joke feeling)- thing is this is a multiplayer game so we all kind of bump into each other.. no longer an option to see something anymore. So no longer an option to play that FF7 in a mankini- because now someone is going to do that to all your content whether you like it or not. That said there are many other ways someone could ruin the vibes of the game, like if you just used clown dye choices lol, or not even visuals but if someone was attacking you verbally - that could ruin the whole experience too. So I don't want it to sound like a one direction road, but I do not feel guilty asking SE to consider, at least the next time they do this glamour system, to try and make their system generate professional FF vibes.
I say at least for the next one since I think taking away things always is a bummer, but I've had a few first time dungeon experiences turned into carnival experiences because of certain outfits. Which honestly after the 800th time I've done the content having a mascot is just funny and not even that bad of a experience, like you might go through the game again in Bayek's bathrobe because bathrobe assassin is funny, but the first time you might want to have the 'director's intended vision' and you only really get one first time unless you can memory purge like from a very long break.