Mostly just that it’s there to say, “see, Batman isn’t a complete psychopath, when he’s disguised as Bruce Wayne he can do charitable things too.”
There’s a philosophical limitation to Batman, that’s probably worth thinking about, if you intend to deal with a character like that seriously. Ironically, it’s also the thesis of Watchmen, you can’t make the world a better place by punching random muggers in the face.
Batman (and to an extent, mainline superhero comics) work through the fantasy of being able to solve your problems through violence. Yes, there’s more to it than that (sometimes.) Bad comics embrace this, without realizing the flaws in this approach. Good ones acknowledge it and either move on with their day or use it to talk about something. Great ones actually take steps to addressing this paradox. And some very entertaining comics are willing to sit at the sideline chucking popcorn at the mess.
As with so many other things, Batman usually flails his arms and says, “I prepared specifically for that,” and then pretends the problem doesn’t exist.
Thing is, given the state of Gotham, there’s a legitimate read that Batman is actually making the city worse. He’s functioning as a kind of lightning rod for crazy. Even by the standards of the DCU, Gotham’s supervillain population is barking mad. It also has a contingent of “normal” supervillains, and criminal element, so there must be a causal factor. At that point, it’s not hard to conclude that it might have something to do with one of its most prominent superheros being at least as crazy as the people he’s locking up. Or Scarecrow’s been pumping psychoactive drugs into the city’s water supply for 70 years and no one noticed.
In this context, about the only constructive thing Bats does is help ex-cons get a job after they’re on the outside… except, it might actually be out of character.
Intentional or not, Batman is a huge fan of Thomas Hobbes. He’s hanging from the gargoyles (because that’s normal behavior for an adult), thinking that people are, inherently, cruel and vicious creatures, who will prey on one another unless someone dressed an animal costume puts the fear of god into them.
In contrast, Superman is a huge fan of John Locke, and by extension on the opposite side of this spectrum. He’s approaching the world from the perspective that people are generally good, and if their needs are provided for, then they won’t intentionally harm each other.
Thing is, these perspectives fit the characters and their respective backstories. The guy who is an immigrant from another world, with a sheltered upbringing, and a (basically) happy life looks at people and says, “yeah, they’re basically okay, maybe they need some help once in awhile, but they can be trusted.” The guy who watched his parents gunned down in front of him goes, “people suck, they can’t be trusted, we need to put the fear of flying rodents into them or they’ll do horrible things.“
When you put them next to each other, you’ve got a fantastic opportunity for friction. These are two ideologies that do not mesh with each other. It’s not that they’re incapable of discourse, but their fundamental approach to the world, and the way they view people, is incredibly different, and their decisions are as a result.
The problem is, offering criminals a way out, and helping them find their footing is a Locke thing. It’s the kind of behavior you’d see from Superman (or a lot of other superheros, honestly). Batman is kinda a minority, philosophically speaking. You can lump him in with The Question or Marvel’s Punisher, but his outlook doesn’t really fit well with most of the DCU.
So, what we’re left with is, Batman disguised as Bruce Wayne, trying to behave like Superman. And we’re asked to believe that he’s trying to make Gotham a better place by engaging in behavior that honestly doesn’t mesh with his philosophical outlook on state of nature. Which also requires that he’s developed the kind of introspection necessary to understand that the way he views the world is not the only possible “correct” perspective, and that’s not supported by the way Batman’s written.
You could legitimately suggest that he does this as a show of respect for Superman (and most of the other superheros he interacts with), or that it’s an attempt to further disguise his dual identity; except, that never really happens. It’s played painfully straight.
Honestly, I think this is simply a holdover from an earlier iteration of the character. Adam West’s version of the Caped Crusader was a lot closer to the Big Blue Boyscout, ideologically. West’s version having rehabilitation programs made sense. We’re also talking about a version of the character who paid parking tickets on the Batmobile and wouldn’t allow Robin to enter bars because he was underage. (Though had no qualms about Bruce Lee beating the snot out of The Boy Wonder, oddly enough.)
The rehabilitation efforts have limped forward, while the character exercising them has been completely re-imagined. It’s kept as a legacy element of his character, without really considering that it makes no sense for the current version. Off the top of my head, I’m not sure exactly when this happened. I’m inclined to point at Frank Miller’s Batman: Year One as the turning point. Though it could have been at pretty much any point in the 80s.
Either way, it’s persisted. We still have a version of Batman that breaks character because it made sense fifty years ago. This is a consideration when you’re working with characters who’ve passed through a lot of different writers. They’ll all add things that make sense to them, but the overall essence of a character can be altered. Along the way, you’ll end up with baggage that doesn’t mesh with the character you’re working on. At that point, your choices are to jettison it (if you’re doing a fresh interpretation), or try to find a way to reconcile these elements together.