Yea it was nice to see awesome characters talk to each other. But they were talking to each other because plot.
Like many have mentioned the characters stopped driving the plot since this season started. They are now just thralls to the plot, taking actions to serve the narrative.
They could of weakened Dany in so many different ways. Think about it. You could of still had Thoros, Beric and The Hound meet up, he can even still have his vision in the flames. But that vision is of ice and fire....and a wall and a castle (eastwatch).
The NK has some walkers and a good portion of his wights assault the Castle. Tormund holds the best he can, Brans ravens go out, Jon tells Dany he needs to go, they all go to Eastwatch, battle happens dragon falls, all ends to same result. You introduce Gendry somehow in ep 7 and then take it from there as far as the Cersie shit and Kings Landing goes and leave us waiting for the ultimate confrontation for s8.
But no lets capture a zombie with 7 dudes in a blizzard against the NK and hundreds of thousands of other undead, make it out alive, show Cersei.......profit?
Lolwut.
But who knows maybe that all happened so they could wrap up Coldhands' character arc. Benoiff even said it himself. "He saved Bran and now he saved Jon".