I've kind of had enough will arguing the merits of TDKR, for the most part people don't listen. I actually didn't even read all of what you said before because I didn't want a headache. I did read this^ post though. Yeah, killing Batman and having him fail would be extremely ballsy and original. And yeah, it would piss off the audience. Not because it wasn't a happy ending, but because it would mean Bruce's character arc and the film's thematic meaning was never resolved. Which would be dumb and would make it a bad film.
I will leave this threat now forever.