At an EPIK workshop last year, I heard that there would be several "approved" textbook programs, and the schools did indeed get to "choose" from the approved vendors. The kickbacks and profits of the textbook publishers, and their relationship to the education ministry and the ruling party, as well as the local school districts, must be a factor in this.
As offensive, inappropriately suggestive, and just plain wrong the current textbook series is, from the Korean pedagogues point of view, it serves the function of keeping children away from English language based culture that has not been mediated by Korean translation. Additionally, the tests designed around it have proven to be significantly obscure, allowing the testing to serve the historic gatekeeper function: That is, a test which helps to winnow a serviceable elite, not a test of actual ability or knowledge. Notice how the tests measure the ability to relate certain Korean concepts to other Korean concepts in the "correct" way, with the English language keys thrown in as a tertiary check on "correctness".
The elementary part of the old curriculum was anarchic enough that rational approaches to grammar could be used effectively within its framework. And for Korean teachers unfamiliar with, and quite possibly resentful towards, English, the old curriculum allowed the schools to spend a little more time honing the basics of Korean with their most recalcitrant charges, under the guise of studying English. At the more advanced levels, the method of having to explain everything in Korean, the memorization of equivalents ad infinitum, and other methodologies, helped to prepare the students to invest further in the Hagwan and tutor industries, perhaps developing them into lifelong consumers of this commodity inappropriately labeled as English. It's the Korean economy, . . . . .
Joybot0's suggestion that we pool our resources in digesting these changes is well received. We'll be in a better position to exploit the upsides in what will hopefully be a mixed bag. There may even be some evidence that the old Korean paradigm of focusing myopically on East Asian reference points is starting to shift.