There's a bunch of interesting things going on around your question. The most straightforward way to unpack your question is to back up to the rise of public education systems in the mid-1800's.

The first thing that's helpful to understand is that until relatively recently - like 1950's recently - the role of education, especially for children and young adults, wasn't about preparing for adult life in the way we think of it today. For centuries, the general theory of learning was that the brain was basically a muscle. If one wanted to get smarter, one had to learn lots of things. In effect, everything beyond the basics of reading, writing, and numeracy was unteachable. The goal of teaching wasn't so the young person learned something they would later use, it was so they got smarter. To borrow from a previous response of mine.

For most the 18th and 19th century, students (generally boys and young men, generally from the population with access to power, likely white) studied Latin, Greek, maths, sciences, logic and rhetoric. The general sentiment was that learning hard stuff made one smart and so the goal was less about learning useful information and more about learning stuff for the sake of learning. This meant there was a hierarchy of curriculum. Math and science were at the top with history and literature at the bottom. It wasn't that educated boys (and sometimes their sisters) didn't study history and literature, it was those pursuits were seen as less rigorous than the content at the top of the hierarchy. Studying history, for example, was seen a bit like doing a short run in the midst of training for a marathon.

A sea change began in the early 1800's or so with the rise of the "modern" curriculum. Politicians and others around the world saw the power in having an educated population and this meant figuring out what that population should know. Different countries - and in the United States, different states - followed different paths, but pretty much every system arrived at the idea of breaking students' days into chunks, each chunk assigned to a different subject. This more modern curriculum often included Latin and/or Greek but evened out the hierarchy; now things like physical education, literature, poetry, music, art, and history were seen as equally as important to the development of a young person's mind and their future as a citizen.

The rise you noticed in creative writing courses is concurrent with the idea of having a major. Until the modern era, a young, non-disabled, white man's (maybe white woman's, occasionally a person of color's) college experience was relatively narrow. This expansion of the college experience as a place for self-discovery corresponded with an expansion of the student body. While some colleges and universities did offer different tracks during the late 1800's and early 1900's, it wasn't until the 1970's that the idea one could earn a degree in something "unteachable" like creative writing firmly took hold. The creation of the Masters in Fine Arts (MFA) cemented the notion of mastering things through education previously thought to be innate or born skills.

The sense you have that people mocking different majors or content areas stems from a lot of things, including the hierarchy I mentioned. Even in the modern era, we tend to think of content in terms of difficult being equal to worth. That is, many people put math and science at the top and the humanities below it. It's also worth mentioning that there were periods and places where students were offered, or forced to take, courses that focused on things like social skills. For example, most young women attending public high schools in New York State in the 1950's would likely be required to take a class called "Home Economics" or "Homemaking" which included a final exam with questions on being social at a party or entertaining their husband's boss.

Generally speaking, the school curriculum in any given society generally focus on the things that society feels are important for children to learn, be it explicit like planning a party, or implicit, like algebra and the corresponding ability to problem solve and logic out an problem.