Not true...
DC's two flagship characters are not a guarantee for box office success.
Remember these?
To his dying day Joel Schumacher apologized to the audience for making Batman & Robin.
And while it wasn't an outright flop, Superman Returns under performed and bored audiences almost to tears.


The main problem with DC films is that they're repeatedly trying to recapture and recreate the formula of the 3 Nolan Batman films.
If they were smart, they'd realize that not every comic book property is SUPPOSED to be dark and grimey.
But when they place each character in their appropriate light and treat them with the proper love and respect they deserve, they are all almost always a
surefire hit.
Examples: