Thank you! :)
Speaking as someone who is currently suffering from really bad ESO burnout...
--There are huge expansions on parts of the lore
--The visuals are beautiful
--We get to see parts of Tamriel we've either not seen before or have not seen in a very long time
--The new content has been scanty as of late (yes, even including Vvardenfell. That's the first new actual landmass map the game has had in about a year).
--Zone chat has been getting increasingly toxic
--The game has gotten progressively more grindy since it came out
--The Crown Store has been gradually taking over
That said, for a new player there's plenty to do. Zenimax just has a habit of ignoring the needs of long-term players and subscribers.
This changes with the Morrowind 'Chapter' FYI. See below.
I remind that 'it's in a Dragon Break' is pure fan speculation.
If you have Morrowind, all your characters will start on a boat and get captured by slavers, then you end up on Vvardenfell regardless of Alliance. You can start the original main quest by going to the mainland, talking to the hooded figure that approaches you and completing that quest. So no you aren't locked out. :) The only thing you can't do is the new tutorial on an existing character, but there's a side quest that is sort-of equivalent for existing characters where you go to the island the tutorial takes place on and attack the slavers.