Those are some great povs.
Yeah, Alan Moore is displeased with Batman: The Killing Joke because he looks at it as not as great and meaningful as his other works.
The Swamp Thing Saga is about environmentalism, V for Vendetta is about fascism versus anarchism, Watchmen is about determinism, questioning authority, and the human condition. Batman: The Killing Joke is not about any big world themes, it is about just Batman and the Joker.
The perspective that the Joker's origin from Batman: The Killing Joke might not be true is open to discussion I though I look at it as pretty definitive since it has been supported by DC and remains unsurpassed, but I can see how some might question it with DC constantly having retcons .
I look at the Joker's line in Batman: The Killing Joke at the end simply about the Joker being so nuts he cannot accept his origin. Since Alan Moore has not commented one way or the other about what the meaning of line is, I can see the differing views to the meaning of such a line. Although with DC's past support of the origin in this graphic novel, I pretty much look at this issue settled.
Ed Brubaker's Batman: The Man Who Laughs does in several ways support Batman: The Killing Joke. It sets up the Joker as a victim of society who wants to get revenge on society for ruining and taking away his normal life. Batman even figures out that the Joker must have had some sort of normal life in the one shot and that when he lost it he went mad. However, what that normal life was the Batman does not figure out.
Yeah, with DC it is hard to know exactly what they are up to. The new Batman: Confidential origin really feels like an Elseworlds Tale, yet according to DC it is the official origin, however DC also still calls the Joker's origin in Batman: The Killing Joke as the definitive origin as well, so confusion is bound to happen. Anyways I think we can all agree on that Batman: Confidential did not live up to what it could have and is far from having anything really to do with the main Batman titles.
The comic book Joker written by Bob Kane, Denny O'Neil, Steve Englehart and Alan Moore is very different from the Tim Burton and Bruce Timm Joker.
The comic book Joker was Red Hood, is a thief of various jewels and paintings, comes up with insidious schemes, does not want to know the identity of Batman and is obsessed with insanity.
The movie and animated Joker is a mobster assasin, comes up with schemes concentrated on getting money, wants to unmask and kill Batman, and wants to live forever.
Although both fell into a vat of chemicals and their appearance is similar, these are two completely different characters with different personalities and origins.
When did Terry become part of the DC universe? I recall that in a comic book there was an alternate future where Tim Drake was wearing the Batman: Beyond costume, but that is it.