I care!
Long shot for sure but he probably thinks he has a better chance with a small group and some stealth. Sending a bigger contingent all but guarantees a battle in which everyone dies.
Story necessitates Jamie gets away so he can meet Tyrion to set up the rest of the season but yeah agreed, bit silly. Can't think of another way they could have gotten clear of the battle though.
Needs to kill someone to do that. She probably figures that kinda sacrifice is worth it to wipe out the Freys, not so much for a bit of spying.
last point on arya is fair enough.
But the other points not so much. Just because it doesnt help the plot they want to have is not excusable for an ridiculous plot hole. You cant just have ridiculous absurd things happen because it would ruin your narrative otherwise. In this case, however, it wouldnt of even ruined the narrative. Catelin Stark let Jamie go before to help her cause. No reason Dany couldnt now given they want a truce with Cersei and she has no real beef with Jamie unlike the Starks. It actually would of prevented another plot hole of Tyrion and Davos just rowing up to Kings landing with no one noticing there boat. Its a time of war and they dont have the Kings guard or military partolling the waters right outside the castle? seriously? The notion of a hidden cove right in front of the castle is silly.
And on Jon why does Jon have to go. He has a responsibility to the Northern people to help them prepare for war. He is now their king. Why would he send himself. It made sense why he should go to meet Dany. But to lead this suicide mission just cos he has seen them before doesnt really pass the mustard as an even slightly valid reason. All he did is fight them and got lucky cos he had the right sword. Its not like he can negotiate with them or knows how to sneak around them. Also not sure how you can even use stealth with zombies. Its not like they can sneak into their camp and pretend to be zombies?