i think she represents the inner mad woman, the side of us that destroys us and tears us down, the critic, the self-saboteur, the deep shadow--she is Innana's sister, after all, and Queen of the Underworld. That part has to be faced in the initiatic journey. She is pacified by the small creatures who sympathise with her and croon to her, and so she releases the decayed meat of Innana, to be in her turn soothed and healed, and ressucitated. Clearly the deep shadow has to be faced, but with empathy. She is unhappy, angry, wounded, mad with grief, which is why the little creatures and their understanding have such an effect--no-one loves Erishkegal. She's the traumatised core, which devours.
Notably when Innana gets out and the demons follow her, she turns them on her faithless hubby Dumuz--she has learned to direct the demons where they belong instead of letting them devour her from the inside.