Even if the HSA account was not available, wouldn't the health plan still be better for most people?
True.
The HDHP stands alone as a superior plan to any copay arrangement.
The HSA allows the client to fund OOP expenses on a tax favored basis. At the very least, they should fund the deductible and keep it fully funded.
The added bonus of accruing money for post 65 medical expenses is a reason to fund to the max every year, assuming they have funded their retirement first.