Feels.

But Kal only found out about his true parentage when he was an adult. Batman grew up with the knowledge that his parents killer was still out there. And his parents weren't the only ones he lost, everytime he let his guard down, someone he loved/cared avout got hurt, which would explain whe he keeps up the darkness.

You are correct sir. And, as the movies and later comics indicate, Batman is kind of the reason why Gotham has so many problems. No matter how hard he fights, the cream of the crazy crop will always rise, and he'll always have to stop them. Tangentially, I keep thinking back to the TV show Angel, when he decides to give up his crusade and go for broke in one last blaze of glory. The difference being of course, that Batman can go on for perpetuity, and people are now clamoring for the dark and gritty stuff.

He's not the reason for all of the crime, but for a lot of the supervillains. But if he stops now, it doesn't mean that the villains will. He's also a key member of the JL, his dark and serious nature help keeps the team grounded, even under pressure. The thing is, the world does actually need a Batman. It brings a sobering reminder that we can wallow in our problems, or we can channel our depression/insanity into something productive.

I've heard it said that Batman and Gotham is how America sees itself at night (or in the darkest times), and Superman and Metropolis is how America sees itself during the day. Batman is the check and balance to the JL, as seen in Doom, and, at the same time, the wild card. I've always been fascinated by the dichotomy between Supes and Bats, how they balance each other out.

True true, they're both wild cards in their own rights. The JL wouldn't be able to continue if either one of them were missing, its like yin and yang.