ZOS split the Morrowind chapter into 3 parts. Battlegrounds became base game. Warden class became a separate upgrade purchasable for crowns. The Vvardenfell zone became the Morrowind DLC, purchasable for crowns or through ESO+.
If you want the Warden, you only need to buy the Upgrade.
Good to know, wish I'd realised it *before* I got the DLC, I would have bought the class before the zone... That will teach me to read the fine print in future; forgot that the purchasing process was like the death of a thousand cuts.
Edit- Scrub that, you need to get the zone to get the class anyway. Guess it's another way of pimping ESO+