I know very little about the comic book versions, but this series struck me as a clear sidestep from the overall character design in that regards. Not necessarily a bad thing, like you say, any long running character has various iterations, but Batman has always come across to me as being a character formed almost wholly by the murder of his parents, so such an opinion re Ra's al Ghul feels quite a big sidestep.

Perhaps if Nolan leaned in a bit more and asked e.g. "what if Wayne turned out less principled and more psychotic? " that could've been an interesting take. Take Batman almost wholly out of the lore and suggest an alternative. Perhaps too risky even for someone at such a high point in his career!