Very distressing story and I would venture to say the old Northwest would not have treated you so dismissively. The NW Asia network had an excellent service reputation.

I flew ICN-NRT-SEA a few months ago in the midst of the NW-DL brand changeover and the terrific veteran NW crew was most nervous about what the future held... they knew DL has no brand equity in Asia, and they feared the DL service standard would not keep attracting customers out there... if enough people are treated like the OP I would say their fears were justified.