One of the constant reservation everyone has right now is basically the lack of WPVP and the intense fights and rivalries that are caused from such events. However, lets not be quick to comment without much information.
It is important to note that the premise for TES:Online at launch is the fight for the Imperial City i.e Cyrodiil. And Zeni Max and Beth want us to stay focused on the fight. You have 3 alliances all fighting to gain control of Cyrodiil. Also to be noted is that at the same time Beth doesn't want us to forget about the big problem facing us while we go and create rivalries in smaller parts of Tamriel. I think the battle for Cyrodiil will only open up the door to bigger guild wars and even greater rivalries when you have guilds from the same faction joining forces to bring down the opposing faction guilds.
It makes perfect sense why regions would be locked at launch since these are hard times and no one outside each Alliance can be trusted. I am sure if they find it makes sense they would open the world in future expansions. You have to understand that no new MMO at launch can go toe to toe with already established MMOs in the market that have years of content behind them.
When people are comparing the size of Tamriel to WoW, we forget that WoW has been out for 8 years now, released 4 expansions, each one adding a ton of new content and continents. I think its safe to say that people have spent hours, weeks, months and even years on RPGs such as Morrowind, Oblivion and Skyrim and still come across something that they have yet not discovered every time. Now, if I did read correctly, the devs did say that the world size in the MMO would replicate the size in the RPG which is quite lot to cover. So now the Ebonheart have the entirety of Morrowing, Skyrim and the Black Marsh to discover.
So I personally think people need to back off and let these guys do their job and see where it goes. A lot of people are signalling the death of the MMO before it even goes live cause the lack of WPVP. I think those are valid concerns, however, it fits in right with the lore and the current situation in Tamriel.