A game mechanic from the series is go anywhere do anything ... changing the topic to whether all provinces are available is some kind of logical fallacy.
Well please do point me to the MMO where there is more to do than raid parties and go fetch quests. Like where you solve mysteries or try to make a real impact on the world.
Just look at Star Wars Galaxies when it first launched. It had 32 unique professions, dealing with a wide assortment of combat, crafting, and social activities. The developers gave the players the tools and it was up for the community to create their own Star Wars experience. It had a huge learning curve. But once players got into the game, it had so much depth and complexity that most MMOs today don't even come near what Pre-CU was. Making MMOs more casual, mainstream, and accessible has ultimately been the turning away of such in-depth and intricate systems such as this. We even see elements of this from Arena all the way through Skyrim by what BGS calls "streamlining" the game.
Back on topic. There is still a lot we do not know in regards to PvP, and there are the advanced features that ZMO has yet to reveal. But, the limiting of exploration (if to be true) would be a grave disappointment for many TES fans. As stated above, the one core principle that BGS has followed since Arena has been to "go wherever you want and do whatever you want." ESO could very well be the first game in the franchise to truly break away from that core element of TES games. Not to say that change is a bad thing, but it definitely could affect how people perceive and judge the game.