Classic and Progressive Classic are both “perks” for paying your Retail subscription. It’s why they’ve not broken it down so that people are paying up to three different subs for what is three different games.
Retail is, and will likely always be, their bread and butter. Now, perhaps they’ll change their mind in how they handle things in the future, but as it stands the Classic and Progressive Classic games, they’re only playable for folks who shell out for their retail subs. That’s what you’re paying for, even if you’re using the Progressive Classic’s token system.