First off, I hate Superman Returns. I mainly hate it because it had so many good things going for it, but screwed it up beyond salvageable. I could go in detail, but I will spare people that for now.
However, I would like to quickly contest the misguided view you just posted above. Maybe, maybe you saw a different cut of Batman Begins than I did.
But I did not.
He did not said in the movie "I have failed my parents." Maybe you have hearing problems? No, this is an exact quote of what he said.
Bruce: What have I done Alfred? Everything that my family...that my father built...
Alfred: The Wayne Legacy, is more than bricks and mortars sir!
Bruce: I wanted to save Gotham...I failed.
Big difference than what you stated.
Bruce would love to forget his parents. However, I think everybody always has conflicted love with there parents. Not only would he like to forget the past because it hurts him too much, but he saw his parents that while noble were foolish because they never took action. They built the city and improved it structurally, but he never thought they actually helped the people.
However things change with what Ras tells him. That they originally tried to ruin the city economically to have the city destroy it self. The only people who ever stood up to him were his parents. They gave everything about them self to make sure Gotham did not economically collapse to prevent it's future doom and when they gave the last thing they could give...there lives...it shocked Gotham back into apathy. As Bruce said, people need dramatic examples to make people do this.
Bruce however was selfish at the time. Like Alfred said, Bruce was making this personal fight. A fight for revenge on his inner demons. To be a true hero, he has to be selfless or he is just another vigilante.
When Ras came in that night, Bruce's whole plans seemed to have been for nothing. Ras out trumped him all along, checkmated him. Ras is better and more powerful, they make great pains in the movie to show that Bruce was always nothing compared to Ras.
Ras also warned Bruce about compassion. If Bruce had made sure everyone in the LoS did not make it out alive, all these people now would not be dead and ruined. But no, due to Bruce's "flaw" Gotham was now going to suffer under the fear gas. This was Bruce's perception in the Batcave.
He was mad about failing his parents because they stood for Gotham, which is what he was truly mad at.
He wanted to save Gotham and at that moment he failed.
Besides, who said he was going to give up? He was just depressed. Hell, many people when bad things happen to them want to kill them selfs. Most people do not go through it, because there depressions leaves. Often by talking to someone who can lift your spirits even though you think it is the end of the world with no hope in sight. Insert Alfred.
That is what I love about how Ras goes down. Ra's biggest flaw is that he cannot understand the good in people. He has no concept of hope. That is why I love that Ras is not beaten by Batman directly, but from a lowly "rent a cop".

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