Re: The Joker sized elephant in the room
I see your argument laderlappen, but for #2, ppl still bring up those people. Especially when something similar happens and they compare the people involved. And your #4 reason is what a lot of people on here keep forgetting about these movies. This is a realistic take on the Batman universe and is very much supposed to feel "real".
And I'm sure there is going to be a point in the movie where it will be relevant to mention the Joker. In no way am I wanting someone to out of the blue say "hey! You guyz remember the joker man? Wasn't he crazy?" because that would be, well, pointless.