The show spent the last several season telling us that North vs. South was not the important battle though. I do agree, there was no way the Night King, as is at least, was going to win the throne and everything is dead at the end. I didn't think it would be that grim of an ending. I do think they could have wrote it so the Night King didn't die last episode, I don't think that was needed or necessary, but I don't think ending that storyline was either mostly because I, personally, feel like the show cut that whole "what are the others" part of the show into just zombies. And if thats the case, fine, but then all the symbolism and azor ahai and prophecies that were in the show all along feel kind of meaningless with regards to the long night.
I guess maybe the show can still add things in to make explanations, maybe via Bran, but putting the dead army as a plot device just makes me upset.