[LibertarianLiz]

I believe that Bran explained in the last episode that the Night King wants the Long Night to return. It seemed to mean that we would lose what makes us human, our emotions, our memories; and, darkness.

The Night King and his dead army can live in that environment --- humans really can't.

[HamiltonJay]

That’s a pretty weak motivation IMHO.... Not saying its not all we are getting, but that’s almost a throw away... “They are doing it because they are evil”...that’s all...

Given this has been 80 episodes by the time it is all through, I would expect some more back story on the Night King and his motivations.

We will see if we get anything...