Marvel didn’t expect Black Panther to be that successful

Let’s start with the obvious: Batman and The Dark Knight were both about Batman vs The Joker. Both have the Joker attacking the mob and inncocent people. Both have the Joker kill someone Batman loves, his parents in 89 and Rachel in TDK. The final confrontation with Joker ends with him falling off a building and Batman shots a grappling gun at his leg. 

The Dark Knight is essentially a remake of Burton’s Batman.