One of my complaints about Begins is that there wasn't enough of Neeson's Ra's in it. He was a joy to watch, and chewed the scenery every time he was on.
"If someone stands in the way of true justice, you simply walk up behind them and stab them in the heart".
I actually think this is why he kind of flew under the radar, because he
didn't chew the scenery as so many over the top Batman villains had before. His interpretation was very true to who Ras is, and because of that, the role was very understated in it's execution, with really no outrageous acting anywhere, which was absolutely the right way to play it.
That quote you used in your post illustrated their weird relationship. This is a man who can walk around and hold a conversation seconds before burning Bruce's mansion down and leaving him for dead, and making it believable for him to do it. It was genius.
Yup, and I'll agree with you, but also add, that I think Nolan can't really juggle multiple villains on screen properly. I agree, I would have loved to see more of Ra's, but for the most part, he was alright, but Scarecrow was so underwhelming to me. I wanted to see more of him, and I feel like they barely used him at all. The same thing with Two-Face in TDK, in that, I felt they barely used him.
I actually think handling multiple villains is one of Nolan's biggest triumphs, because they're used to serve the story, and not vice versa. I can't honestly think of how to change anything around to allow more time for the Scarecrow or Two-Face that would have made sense in their respective films. Now I will say that I think he should have left Harvey alive, but beyond that, I can't see where everything didn't fit almost perfectly.
Crane was more of a renegade outsider to the mob who was useful for a time before he started doing his own weird things. Once Batman caught up to him with an antidote, what else could he do? His fingerprints still are all over the movie, and it's his ability to weaponize the toxin that even allowed for the climax. If we're talking a grounded hyper-reality which Nolan was going for, than it's completely legitimate that Crane would be a pawn for Ras, someone with aspirations for world "cleansing" and a means to accomplish it. It's not like Ras would tolerate Crane in any other capacity anyway, he became a criminal, something Ras doesn't fashion himself as, and something he doesn't tolerate.
Dent of TDK isn't the same as the one from the comics in the sense that, he seemed to only be vengeful towards those he felt responsible for Rachel. It's not like he was after a life of crime, like he told Gordon "you think I want to escape?! There is no escape from this!" He was fine with killing himself right then and there if the coin had told him to do so, and he wasn't exactly worried about coming out of there alive afterwards either. In that context, I think he was handled the correct way, although it would be interesting to see what would happen if the public had found out about him.