Siva is not just the destroyer. He is Brāhman, He is Purusha, He is Sadāsiva, He is pure consciousness. He drank halāhal (the poison coming out of the churning of the Ocean) to save humanity. Will a destroyer do that? He brought holy river Gangā on earth by carrying her weight in his matted hair. Will a destroyer help nourish the earth?
He is not just the destroyer. He is all five: the Creator, the Preserver, the Destroyer, the Māyā (illusion) and the Grace. The word Siva means the auspicious one. He embraces everyone. He is Pashupati, the lord of all creatures. For Siva, there is no good or bad, there is no right or wrong. He is the friend of demons and ghosts. He wears snakes around his neck and carries a skull as his begging bowl. He smears ashes of the dead on his body and dwells in cremation grounds and icy caves of the mountains. Kubera (the king of yakshas), Ravana (the king of demons) and Shukra (the guru of asuras) are among his greatest devotees. There is nothing inauspicious when we are talking about Siva. And there is nothing else other than Siva. Om Namaha Sivāya.