Yes, real insurance (like car insurance or renter's insurance) will always have an expected value that is negative - the expected sum of all future payouts must be less than the sum of all future premiums paid. So insuring against completely predictable events is never worth it unless someone else pays for it, and even then it's less efficient than if they gave you the extra money directly.
Not all dental and vision benefits are completely predictable and routine, but the overwhelming majority of covered benefits are, unlike health insurance (which isn't really "insurance", despite the fact that we use the term).