Star Wars is not exactly known for its depth of characterization-- nor is George Lucas known for his depth or insight. The death of the aunt and uncle free Luke up to go off on a big adventure where things blow up; they are never mentioned or thought of again. Leia is both tortured and forced to watch her entire planet of billions of people incinerated, and it has no long-term effect on her. In the prequels, her mother is actually turned on when Darth Skywalker commits genocide.
Thinking about the SW characters as if they were real people is just creepy. It's best to just sit back and watch the explosions.
People in Star Wars, especially the OT just weren't emotional. In addition to these examples, you had Han Solo, after spending a couple of years frozen in carbonite and nearly fed to a giant vagina in the sand after being woken, the first thing he does is lead a rebel strike force against the Empire's premsuably most well-defended facility.
That's one of the things I like about Star Wars, what should be significant life changing events are just shrugged of by all concerned. Nothing is dwelt on, everything gets swept under the rug. Well, almost. Luke did have trouble accepting Vader was his father, and Leia had some trouble dealing with Luke being her brother. But still, they worked this stuff out a lot quicker than most people, who might require some pretty extensive therapy in those situations.
That's something that worries me about Abrams doing Episode 7. He's so into emotions. Someone's probably going to cry in that movie.