The three mistakes you note were well within the character arcs for those particular characters, Ned always put what he thought was right before what he thought was strategic. Jaime, especially young Jaime, was impetuous and full of the hubris that comes from easy privilege. Cat was almost as much about payback/vengeance as Cersei.

I don’t mind characters having tragic flaws, I mind new tragic flaws being created out of wholecloth because it suits some new capricious storytelling urge.

My objections are not to characters acting the way they would normally act it is to changing the characters to fit absurd but entertaining ad-hoc “made for television” events but rarely in ways that service the story.

The rest I agree with, we are often a cruel and stupid society.