These references don’t necessarily enrich the moviegoing experience for mainstream audiences who aren’t accustomed to the DC world, but they go a long way towards satisfying fans who can pick up on them.
This is far from the only reference to the greater DC universe that we have seen in a DCEU film.
Man of Steel similarly included Christopher Reeves’ face over the face of Henry Cavill’s Superman in one very brief scene, Batman v Superman: Dawn of Justice featured a reference to the animated Batman classic Mask of the Phantasm, and Suicide Squad was packed with nods to other heroes in the DC lore.