Bruce did have a parental figure: Alfred. And Leslie Thompkins, in some continuities. It's not like he grew up as a feral urchin on the streets. He had a good, sheltered upbringing, a life of prosperity that enabled him to get a thorough and eclectic education and obtain the skills and resources he needed to apply himself to any calling he chose. And the calling he chose was crimefighting, the effort to get the predators off the streets and prevent other children from having to suffer as he did.
I've never been crazy about the post-'80s idea of Batman as some borderline psychopath acting out an elaborate revenge fantasy. That just doesn't add up for me. Even in the wake of tragedy, someone raised in such a nurturing and prosperous environment would probably turn out to be pretty well-adjusted, for the most part. Sure, it would take a certain obsessiveness to become Batman, but no worse than the kind of obsessiveness that makes Reed Richards a great scientist or Lois Lane a great reporter.
When I was looking through "To Kill a Legend" yesterday, I came across a couple of panels where Bruce thought, "I guess I'm lucky, in a way. Whenever it gets too painful being Bruce Wayne -- I can always become the Batman! I wonder how normal people manage to cope?" I found that refreshingly different from the later perception of his Batman role as something intrinsically unhealthy, as a failure to cope and grow up and move on. The pre-Crisis, pre-Miller Batman had
moved on, had gotten past his parents' death, but still kept on being Batman in order to protect all of Gotham.