Not asking what it did as a storytelling device. What was the goal of the League and why did they do things like they did.>Bane is cruel/Members of the League are devoted
The first sewer scene shows that quite clearly>Bane makes plans as opposed to the Joker
He does make plans, I could have gathered as much from watching the rest of the movie. And the Joker comparison doesn't work when TDK's first scene is how everything goes according to the Joker's plan.
As for the characters's goals>Faking Pavel's death
If all it takes in that universe is to put someone's blood in a corpse, there had to be way more efficient ways to do things. A single car accident or a robbery wouldn't have appeared more suspicious than a plane wreck missing it's wings and full of gunshots.>But they had to learn what Dr Pavel told the CIA
What did they learn exactly? Bane didn't knew anything more after the crash than before.>Probably was off-screen
Doubtful (Pavel wouldn't waste time saying he said nothing if right before CIA and him had a chat that Bane could have heard) but possible. If it's the case though, the same result could have been accomplished by off-screen torture of the good doctor.
In short, all the plane sequence did was to fake Dr.Pavel's death in an easily disprovable way when there could have been a much easier and convincing way to do so.
The first scene should have been about how Bane and his men "grabbed their prize" the first time, not how they caught him again after they brought him to the CIA.