That "good" people argue and talk out whether or not they should press the button on the detonator...

Exactly. And yes, Batman is only human:

The Flash: "What's your superpower again?"
Batman: "I'm rich."

He struggles with holding on to his principles because the Joker is his perfect anti-pole, it's the Joker that confronts Batman with the evil within. But ultimately both hold fast to their intended roles, which could also be seen as order vs, chaos. Also You have to make a distinction between Batman and Bruce Wayne; Batman is not a man, he is a symbol; "anyone can wear this mask. Batman could be anyone." Bruce Wayne would have killed the Joker, but as Batman he can't...

It's the constant battle between the two extremes that ultimately paint a picture of the drab dark-grey that is Gotham and the true nature of men. This is not only accomplished in this movie, but in the entire trilogy. At least, that's how I saw it after the ...th time watching the movies. The beautiful thing about art is that it's always in the eye of the beholder and we're allowed to see and interpret the artist's intentions for ourselves, and I certainly see where your interpretation makes sense too :-)

About Bale: in my opinion he did okay. But that voice.... ;-)

Thanks so much @kipswolfe for this great response; I hope to read more of those in the future! 😊