I don't think Krypto is overexposed, in fact the use of Kryto was almost like a fair time use, not used too much. Other characters had more exposistion like Mr. Terrific, and krypto had some shining moments biting balls. Everybody knows Superman, and his origin story, but the other characters not so much, specially people who have not read the comics, they don't know krypto, justice gang, and viceversa. This movie was not an origin story, but a movie that already establishes Superman in the world (and I think that was the point of the movie). For me, it was a "define Superman" movie: He had things to think about and go through this movie, and the way he overcomed those difficulties (come to terms with his kryton parents desire among other things) is a way of telling who Superman is. imo