Originally Posted by Happy Jack
I believe that moment was acceptable because Ra's had put himself in that position. He tells Batman before boarding the monorail that his fate would "lie with Gotham", meaning he was on a suicide mission. By the time Batman had subdued him the train couldn't have been stopped and there wasn't really a way for Batman to save Ghul and himself. The dialogue was iffy, but the circumstances were appropriate IMO.
Actually, he said his "fight" lied with the rest of Gotham, but I can see how it could sound as "fate"
I'm sure the writers (Nolan and Goyer) could've come up with a way of getting Bats to save both Ra's and himself. I mean, kinda like what he did to save Rachel in TDK. My guess is, it was time for the movie to end, so they had to dispatch Ra's in some way. In true Batman movie fashion, Batman ends up getting his bat foe killed and we missed the opportunity to have a Magneto-like presence in the Batman films.