Re: Why did the League of Shadows want to destroy a peaceful city?
The best way to interpret the LOS's motive is to consider them as fundamentalists. Fundamentalism is a reaction to Modernist theology. In Gotham's case, the Dent Act has eradicated organize crime. But there's always a minority whose opposition to change is unflinching. They stick to an idea no matter what. Any crevices they find at the system or structure is used as a reason for action. That crevice in TDKR is Daggett and Stryver. They represent the oppressors that have kept ordinary Gothamites down with myths of opportunity, which they ironically helped to power before BB.