The Batman Who Laughs didn't have superstrength, superintelligence, superspeed or supertech or anything like that to start out with. He was Batman exactly as we have him now and went evil and crazy. This is what Snyder tells us he is capable of doing with it.
There actually have been comics published after the 40s that depict him fighting crime in Gotham rather then taking on multiversal gods, you just need to know where to look for them.
Going from this
Attachment 99587
to this
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Is pretty clearly superhuman. They didn't need to do this to write this comic. They wanted to write this story though, and decided to do it with Batman. And also have the main villian be Batman. And also have the 6 evil henchman who each have their own tie-in comic be Batman. This really doesn't happen to anyone else in DC Comics.
I'd argue Damian dying is something quite bad for Damian as well. Offering up bad things happening to Damian or Alfred or Dick or Tim as evidence that Bruce is the whipping boy of the batfamily as opposed to Damian or Alfred or Dick or Tim seems wrong. Bruce is Alfred's boy, Alfred has all but raised Dick as well. All the bad things that happen to them should be considered to make Alfred the whipping boy of the bat family by that same logic. Seeing Bruce suffer doesn't exactly leave Dick and the other cold either, they care a great deal. This logic doesn't get us anywhere.
Batman was the vocal point in Final Crisis. He was as much the protagonist of Infinite Crisis as anyone else as well. Same with most new 52 events. It is difficult for him to be both the protagonist and have it be his powerset that is making the event happen like the Flash is Flashpoint or the Green Lantern in Darkest Night/Brightest Day but that's
because he doesn't have any powers. That's not him being treated unfairly. If his peak human abilities are threatening the very fabric of the universe I don't think they should be described as peak human anymore, cause we definitely can't do that.