Over the past few years, Korea has become an industrialized country with a globally competitive economy. This means that an increasing number of foreign companies are investing in Korea and many Korean companies are investing abroad. There is also an increasingly large number of foreigners in Korea and of Koreans going abroad.
Those foreigners living in Korea and Koreans who work with foreigners may learn of foreign language. Foreigners try to learn Korean (although an increasing number of foreigners are attending Korean hagwons to learn English or other foreign languages) and Koreans usually learn English, all though languages like Chinese and Japanese are also very popular.
People wonder why studying English in particular has become so popular in Korea. Well the Korean job market is very competitive. And Korea is still a relatively homogeneous country. Therefore most job applicants look alike and have similar backgrounds. Just like graduate schools in the US have lots of applicants with similar backgrounds who may have their sample papers and SOPs carefully proofread, one thing they can not cheat with is a standardized test like the GRE, therefore many schools require the GRE as an additional factor to select students. In Korea, it used to be very hard to select job applicants since they all did well in their applications. However, standardized English test scores have become a good way to select students, as some do well and others don't.
Standardized TOEFL, TOEIC etc. tests in Korea are only a way to select job applicants from a shorter pool of applicants, as those who did not perform well will be eliminated. Companies have no interest in the actual ability of applicants to speak English, although some may also carry out interviews in English. As more and more Korean students perform well on English standardized tests in Korea, some companies have required ridiculously high TOEFL scores as a precondition for recruitment: a 100 score in the TOEFL (out of 120) when most ivy league schools in the United States only require 70 or 80.
So why study English in Korea. Studying a foreign language is motivated by a need. Some need English for economic reasons (getting a job, making money) others for "kinship" reasons (fitting in a foreign community). Most Westerners studying Korean do so to fit in with Koreans (but not all, many study Korean for economic reasons) while most Koreans study English, because as I just said, it is a precondition to getting a good job.
Here are the main differences in behavior between those who learn English for economic reasons and those who learn it to fit in:
ECONOMIC REASONS (MOTIVATED BY MONEY)
-Have a very negative approach towards learning the language
-Refuse to speak the language unless they are forced to
-Always carry textbooks with them
-Refuse to say anything that is not in the textbook
-Memorize lists of words
-Practice grammar with grammar textbooks
-Tend to get very good grades in class
-Insist that writing is more important than speaking
-Insist that "they don't speak the language very well"
-Dislike being corrected but constantly ask themselves and other people "am I speaking properly?"
-Do not talk in class if they are not asked a question
-Give very short answers when asked a question
-May ask teachers lots of questions about the meanings of certain words or grammar
-Very nervous when they speak, may sweat, blink constantly, refuse to look at the person
-Are very careful when they speak and speak very systematically
KINSHIP REASONS (MOTIVATED BY TRYING TO FIT IN)
-Have a very positive approach towards learning the language
-Try to hang out with as many people who speak the language as possible
-Make lots of comments in class
-Only study before the exam, if at all
-Think speaking is more important than writing
-Tend to perform poorly at exams but still pass
-Enjoy the language's cultural products (foreigners in Korea may enjoy watching Korean movies, Koreans may enjoy watching channels like "on style")
-Like to tell jokes, are very relaxed when they speak the language
-Their relaxation means that they are more prone to "cute" mistakes which will not impair intelligibility
-Confident or overconfident with their language skills and highly dislike being corrected
-dislike being reminded that the foreign language is their second language
So yes, most Koreans study English to get good TOEFL scores and know that they may never use English when they get their actual job. Just like students applying for graduate schools in the US memorizing GRE words that they know they may never use once they get admission.