Eurydice enters the play's action only at its end. Why does Sophocles include her death?

Eurydice seems to play absolutely no role in the rest of the drama, but suddenly appears at the end to take her own life, merely adding to the body count. At first this may seem like overkill, but this moment is rather a precise fulfillment of the terms of Teiresias' prophecy. Indeed, Haemon's life is exchanged for Polyneices' - a death characterized by shame and vengefulness. Eurydice, meanwhile, will atone for Antigone's death - she dies much like Antigone, cursing Creon to the end, abdicating any sense of his self-ascribed power.