You're getting a lot of crap, but I kind of empathize with you. Socializing and getting girls has never come easily for me. But you're sort of giving off a helpless vibe, and I think there's probably a lot you can do if it's important to you.
You're SOL on your height, but your muscle mass is quite malleable with pretty low effort. I work out for two hours a week, one hour on Saturday (upper body), one hour on Sunday (lower body and core). I don't look like an nfl linebacker, but it gets me to the athletic end of the dork spectrum at least. I'm betting you can find two hours a week to spare. If it doesn't take, you might have low testosterone, which is easily fixed medically (by taking testosterone, ie anabolic steroids... kind of extreme, and for the record, I don't take them myself, but if you actually have low t it seems somewhat reasonable to me.). Even if you don't want to work out, I don't think being short and skinny is a huge barrier to getting girls. Many of my friends fit this description and haven't had trouble. If that describes you, you may have other problems. If you've left unsaid that you're overweight, that's a lot harder to fix than muscle mass. Probably worth one good attempt to slim down, it works for some people, but doesn't for a lot of others. You may have to live with it.
Which brings me to... social skills. They really are skills. It comes naturally to a lot of people, but if it's unnatural for you, you CAN get better if you try. It takes a lot of effort, but if it's important to you, put some real effort (and time) into it.
Females are not as irrational in their preference for tall muscular men as you seem to think. Tall men make more money on average. So do good looking men. Why? There's two sides to any business: making shit and selling shit. I'm guessing you're good at the making part. Selling is just as important. People like to be around attractive people. Sucks for the non-beautiful, but just a fact of life. But you know what? They also like to be around funny, confident, and friendly people. And you can do something about that.
Being an "unlikable weirdo" wouldn't explain getting no responses on the standard dating sites/apps everyone on campus uses, when the demographics of the college are around 65% female. Part of the problem is that way back in the day, when the tribes were small, it was in the woman's best interest to mate with only the perceived fittest mates around, and her mental baseline of "average" would be set by the local tribe members. Now that we have the media and such showing super-fit males as the standard, that becomes the baseline of acceptable, so it seems like you're written off right away if you're below that. Some time ago before we were so inundated with such standards in the media, the mental baseline would be more realistic, and more males in the local town/area would have a chance. The male's evolutionary sexual strategy has always been to impregnate as many mates as possible, so the change in the media hasn't really had an effect on that end. This ties into my observation, which I've seen echoed on a lot of other forums online, that even the far less conventionally attractive women are increasingly refusing to settle for any less than a male they'd rate at "8/10". There's also a study by OKCupid saying something similar.
I'm going to go out on a limb and suggest that the perceptions warped by "media" are those of people who judge female psychology from lack of digital interaction with their app profiles and pop evolutionary psychology in forums populated by sexually frustrated men, not those of women having the amount of sex they want despite none of the men they meet having the wealth, looks and/or charisma of their favourite film and sport stars.
But I do know that I stressed out about shit like this in high school, then figured out that if you treat women like people and ask them out, some percentage of them will say yes.
Just because you don't have a trait doesn't make that trait "obsolete."
By the way, a large majority of humans in the United States marry and even among the ones who don't marry a vast majority of them have dated. A large majority of people in the United States are not tall and muscular, we come in all shapes and sizes.
You may find this shocking but Women aren't uniform brainless sheep. Women come in all forms with all sorts of different things they find attractive. For example, I don't find muscles especially attractive and tallness does absolutely nothing for me. My husband is overweight and I don't mind a bit, doesn't distract from his attractiveness to me. Some women are even attracted to other women.
(Hint: it actually might be you since 99% of society can somehow manage to get a date)
Looking at japan, that number seems overestimated. That might be your personal experience, but because of survivorship bias - you'd be less likely to meet antisocial shut ins etc.
