From my perspective, it all depends on the person. There are some people who will definitely get over tragic events far more quickly than others. I view Bruce Wayne as someone whom is constantly haunted by the death of his parents for reasons I'm not sure I can explain. It's just a part of his nature, in my opinion.
I recall an old episode of The Animated Series where Batman saves the lives of two kidnapped children to the effect Bullock utters, "Poor kids. Trauma like this can really stay with them." Gordon looks up and witnesses Batman taking his leave and replies, "Yeah .. for some .. all of their lives."
Of course, I agree that all Batman stories shouldn't dwell on that tragic event, but I see no harm in Wayne showing his longing for them once in a while. What makes the character (Batman/Bruce Wayne) unique in my eyes is that he doesn't want to put that horrible night behind him. He has had opportunites (most recently in Green Lantern), but he chooses to hold onto the pain for reasons of his own. And I guess I kinda like that about Batman.
