I'm only making assumptions from what I've read.
You're missing my point though. The bold part..this is part of my point. It's tragic because of this, and because of Ultron, Banner becomes his own tragedy.
As far as Banner coming to terms, well yes. He did come to terms and Tony's beliefs were absolute.
It's not so superficial like you describe. Tony's character changed A LOT from before the final battle in A1, to A2.
Ultron tears them apart "from the inside". And that messes with Banner's head very deeply. It's not retreading anything because it's new. Look at Freud and all his neo Freudians, personality is ever changing. Ultron must mess with them so bad that Banner relapses as I said. It's a lot more than TIH. Because apparently the damage is SOO deep in Banner's psyche that Hulk feels it too. Banner thinks he's of no use and let's Hulk out. Hulk makes the decision to turn off the com, and further the pain Banner feels.
So we got Banner who is terrified of Hulk, and wants it gone, to slowly coming to terms with it..to taking Tony's encouragement and accepting who he is Hulk helps save the world, in phase 1.
Phase 2, Ultron happens and messes with everyone. Ultron, is a product of Stark's messed up self right now. Now Banner is probably having normal doubts again but because of the circumstance it becomes even more amplified. Banner who once came to terms with the Hulk goes spiraling down because of Ultron, and the damage is deep that Hulk feels it.
This is how I see it, and to be honest to me that's a character arc :/