TLDR Some of the most interesting mini-zones are accessible only during certain quests. They should be instanced, added to the world map and given wayshrines so they can be revisited.

I'm replaying DB, and ended up in the Jerall Mountain Logging Camp - wow, they did that forest better than Skyrim did forests. It is a stunning and lore friendly mini-zone, and I've left my character there because once I finish the quest and leave I can never experience it again with that character.

Off the top of my head I can think of other mini-zones I would like to revisit. The island the future Wilderqueen makes/grew up on. The island the Veiled Heritance train people on. The sword-saint school that Sai Sahan takes you to (and may go back to...). The island where you launch your attack on coldharbour. Checking your map in any of these places shows your location in the world is programmed in the game but you are outside of the existing zones. I think the mini-zone outlines should be drawn into the main map both to make it look fuller and to acknowledge that ZOS has already established what is there.

To protect the immersion of first-time players, my suggestion is, after completing the relevant quest you get a wayshrine marker that allows you to travel back to these zones. Instancing out newer players is already done in many areas to allow different players to be at different points in the same quest; Dune is an example, it is a ghost town overrun by Daedra that is restored to being an almost fully functional city.

I hope people will tell me their thoughts, and that the idea gets considered. I don't know how it could be implemented but I expect it will be something between either;
1) Just add a wayshrine and update the world map. All NPC's remain with the same dialogue
2) Also update some zones, e.g. the veiled heritance are no longer training on their island and some Auridon Marines are stationed there. Or even see Sai back in a partially reconstructed sword-saint school. If they did this work then I think they could legitimately call it a minor DLC, and either charge for it in the crown store ('Tamriel:Revisited') or even make the ability to revisit these zones a unique perk for subscribers.

Thanks for reading. I know this isn't the most important thing in the game (maybe I need to quit the 'member berries), but seeing the world map fill up is one of the things I look forward to.