Right on...nice thoughtful look at the situation.  I just wanted to add a few points/answer one of the questions you posed.  As you stated all Korean are compelled to study English when it is clear that the vast majority will not need to utilize it during their careers.  The Korean "English Craze" largely stems from a dedicated government effort to turn Korea into a hub of regional/global finance and business.  As such, they wish to create a society with a widespread English proficient population as a means to provide a comfortable/attractive environment for global businesses to locate and operate in  Korea (as English is commonly used as the language of international business).  This strategy also  includes the generally unpopular FTAs recently signed with the EU and USA, putting Korea at the forefront of the FTA movement. 

       Further, during the decades of Korea's rapid economic rise, nationalistic/in-ward looking sentiments were effectively utilized by elites to encourage/justify the dictatorial top down organization and management of the Korean economy including the sever repression of unions and labor advocates.  Now, as Korea is attempting to shift their focus towards a more open economy/neoliberal order it is causing a great deal of societal consternation as people are being asked to turn away from the very sentiments that were stoked during the Park Chung Hee era.  Whether or not this is a good thing is certainly up for debate, but I just wanted to note that their in an underlying rational undergirding this drive to make Korean a bilingual society.  Thus more than anything, foreigners in Korea often appear as symbols for a wider socio-politico shift the Korean government has been pushing on a skeptical populous.