The age thing: Time passage in comics quite obviously doesn't have to coincide with the passage of real time. If we're going to be stupidly sarcastic about it, does that mean the first comics should have covered him being born and growing up as a toddler? His example is an obnoxious non sequitur.
'Why would you want fiction to be like the real world?': The point is for the reader to fantasize about an attainable solution to major problems, for the writer to provide them with that sense of aspiration toward a tangible goal. A large appeal of the better Batman stories is that it makes you feel like, if you push hard enough, you could accomplish what Bruce Wayne accomplishes. You do that by painting a reflection of reality.
When you break the illusion of attainability too much, the Batman comics begin to dissolve into little more than another generic sugar-high. He stops standing out from the crowd as much, and people like me find themselves looking for other comics that are actually relevant.
Which isn't to say you can't write a good story unless you're realistic, but it's kind of the heart of Bruce Wayne. He's not got any powers, he's a real man with a real drive. If someone can't see the appeal or value of that, they have no business writing Batman in any form.