As others have noted, they are promoting the character as Wonder Woman already. The audience isn't going to be surprised, nor is that necessarily a perquisite to a good film. For example: To go back to TDKR, Anne Hathaway's character is never called "Catwoman," but from pre-release publicity even people who have never picked up a comic book knew from the first second on screen who she was supposed to be. And did that "ruin" the movie? Of course not.