Well, to be fair, many Korean bureaucrats resisted using Hangul for centuries, and Koreans kept three different writing systems: scholarly works and government

Well, to be fair, many Korean bureaucrats resisted using Hangul for centuries, and Koreans kept three different writing systems: scholarly works and government documents in classical Chinese, lower-level bureaucrats using Idu (a system of writing Korean words using Chinese characters with the same sound), and Hangul. I think the move to write everything in Korean only happened in 20th century. Even then, most documents contained a liberal amount of Chinese characters to write Sino-Korean words (maybe due to Japanese influence?), which could be seen well into 1980s. (And these days Koreans decided to put English vocabulary in the position of literary significance, and some would write sentences which are just strings of English words connected by Korean suffixes. Grrrr.) * Also one of the reason modern Korean spelling is so regular is that it's totally revamped in 1930s thanks to the heroic work of Korean scholars who considered the work as means of preserving Korean culture under the oppressive Japanese regime. It involved discarding four letters, adding a horde of new letter combinations to represent underlying forms, and a drastic shift from purely phonemic to morphophonemic script. (Something like English always using "-ed" to mark past tense even though they sound different in parted, picked, and seemed.)