Woah, woah, woah. What's this shit? Dude, you do not understand gender issues
nearly as much as you think you do.
First off, I'll start with the -simple- things you've completely missed and clearly don't understand. There is far more than just "physical sex" (which I'll cover after this) and gender identity. You also have gender
expression, which is actually where you get things like what clothing they want to wear, and you also have gender
roles, which is based around the gender norms of the society you live in. Transgenderism is far more than just MtF and FtM transsexuals; you also have gender switch, bi-gender, third gender, no-gender, and varying levels of transvestitism (cross-dressing).
All of those are under the transgender umbrella, and are about core aspects of people's personality. To further demonstrate you're missing the point, not all transsexual folk desire surgery, and some don't even have that much desire for hormones beyond what little bit is needed to cause the secondary sex characteristic changes they desire.
Now I'll pull in something you said which I actually find offensive. You said you would look down on a man crossdressing, but not a transwoman you've clocked, and have tried to say it isn't prejudice when it is nothing but. You don't know if the person is just crossdressing. You don't know if they're a transwoman doing a poor job at blending into societal norms (it happens, especially early in transitioning when hormones and the like have not had time to do their work). You don't know if they're genderqueer or have some other non-binary gender identity. You simply
cannot tell by looking at them, so
any judgement you make is prejudiced based solely on appearance. Thank you for demonstrating just how shallow you are.
Now, as for your complete misconception about physical sex. What are you using to make the distinction? Whether they have a penis or a vagina? Gonads? What gametes their gonads make? Chromosomes? The genes on the chromosomes that actually make the signals the body uses? The hormone levels made by their body? How their body responds to sex hormones? The formation of their skeletal and body structure? The development of their brain (and if with this, from which of the many, many parts involved in such)? Sex may be a lot of things, but a binary is about as far away from accurately describing it as you could get. This is also made
very clear by the prevalence and just how many types of intersex conditions there are, and I've not even covered the more esoteric ones (like alpha-5-reductase).
So, now that I've covered what the core of the argument is actually about, I'll address what you
think it's been about.
Seriously? It boils down to clothes and fashion? You think the primary issue is because men's and women's clothes fit differently? Have you ever thought of being a comedian with how ridiculous of an argument that is? I know from years of experience wearing both men's and women's clothes that the differences aren't as gender-binary as you think. First, the primary difference, in relation to your argument here, really comes down to that women's clothing is tailored to be close fitting, whereas men's clothing is tailored to be loose and not form fitting. Even taking this into account I've noticed more variation within women's and men's clothing than there is between them.
Even underwear doesn't have as much difference in fit as one might think. I actually have a large penis but wear women's panties just fine, and do find them far more comfortable than any men's underwear, as many non or pre op transwomen do, and I've run across many ciswomen who much prefer the fit of men's underwear.
You can't even say that breasts cause a huge difference, either. I've known many men with sizable pectorals, who would be able to comfortably wear many items of tailored women's clothing (and they did not have gynocomastia, it was just normal muscle and fat tissue expected on males), just like I've known many women who have small boobs (including myself) who can comfortably wear even tight fitting men's clothing. I will agree that large busted women and the clothes for them fall outside of that, but it's still not as much as you seem to think.
"Oh, but what about their frame? Men's and women's bodies have really different base shapes!" Yeah, that in quotes is actually bullshit. The skeletal and muscular frame doesn't have nearly as much difference as the media portrays, even if you look at average people. Yes, the pelvis does form with a different tilt and such, but as far as clothing is concerned it's meaningless. Again, I am able to speak on this from plenty of personal experience and from the experiences of many others who have worn both genders of clothing.
Oh, and who the fuck goes to kindergarten in khakis and a
vest these days? I grew up upper class in a well off city in the '80s and the only times I wore a vest, or saw others doing so, was at church. Hell, one time in 3rd grade when I was very much trying to conform as a boy I wore a long, untucked shirt with a belt over to school, and the most I got was a couple teasing comments from the school bullies at recess. (I was aiming for it to be like a knight's tunic, but if I remember correctly it was my previous school's t-shirt, which means it would have been hot pink with black letters.) Keep in mind I was bullied throughout my entire time at school, including getting pushed down the stairs and beaten up, even with having changed school districts several times (from moving) with there being no stigma carried from one school to the next.
Oh, and you want to know the mysterious secret behind fashion? It's really pretty simple. Fashion designers (including runway fashion, but primarily for stores) and the industry that markets their designs is one of them. The other, actually more important factor, is this: confidence. If you look confident in what you wear, you can make
anything look fashionable, or at least passable. If the person doesn't have confidence in what they were, though, then it doesn't matter one wit what it is, they will not look good in it. Confidence in how you look also comes from being comfortable in the clothes you're wearing, 'cause, after all, if you're not comfortable you're not going to be that confident.
Oh, and regarding the whole thing with costumes... What you depicted is an example of a cheep Halloween costume, which are by far not the only kinds of costumes, even for Halloween. Do you think the actors in X-Men were just wearing leather outfits? No! They were wearing bloody costumes that were made out of leather. I've known many people who make their own costumes, for Halloween, stage, LARP, renaissance festivals, dances, parties, re-enactments, SCA, various conventions, and other occasions, and have them them to be of higher quality than their normal clothes. I've also known some people to wear such costumes not just at home and whatever occasion it was originally designed for, but for going out to eat and such (and not just on the way to or from whatever event).