All in all i agree.
But actually at the time i wanted to learned that expression in order to try to write more naturally to my language exchange partner, which played a really big role in me learning a whole bunch of vocabulary and grammar so it was pretty helpful for me.
But boy do i appreciate your honest comment. :)
And beside, colloquial terms are often what keeps in fun in learning languages for me, whenever i feel discouraged from 'proper' learning, and that has some value too, do you think?
As for going to Korea, haha absolutely, i plan on going this October.
Hopefully will earn the plane ticket money by then.