The case the administration is making is that these old plans had invidious characteristics such as lifetime spending limits and missing "essential" no-deductible coverage for preventative services and birth control. Not sure whether that's an accurate claim for the pre-ACA plans you listed. Presumably ACA's no-deductible requirement applies to the new plan, so while you might pay for irregular doctor's visits, your scheduled preventative checkups should have no out of pocket costs.

But I think that's small potatoes (the number of patients likely to exceed any reasonable lifetime coverage limitations has got to be tiny, and cheaply re-insurable by BCBS if needed). The real cost is likely coming from BCBS' estimate of the change in the risk pool characteristics of this new plan. Namely, it doesn't matter how healthy you are to sign up for the new one, so presumably on average it will be made up of less healthy people. There's also the cost-shifting that has to happen: Plans for older people can only be a set multiple (3x?) more expensive than for younger people, so the younger person's plan must be made more expensive. This is called cost-sharing if you're being polite, and a redistribution scheme if not.