We talked to The Elder Scrolls Online Game Director Matt Firor ahead of the game's E3 showcase. You can watch the interview in full below, but here's a few choice snippets from it.
On drawing in non-MMO players
"This is more a multiplayer Elder Scrolls game than an MMO. [You'll see] very limited UI, nice and clean, not a lot of bars.. the combat system is very much action-based. It's also soloable... you can solo almost the entire game. We wanted to get Elder Scrolls players who were unfamiliar with online games and MMO terms to get in, play, have fun and get introduced to the multiplayer aspects.
On expanding "your world" to "our world"
You tell good stories. We have the main story of the game, that every Elder Scrolls game has - you start out in prison and you end up saving the world... that story is very much solo. You're the hero. The NPCs talk directly to you.
We promote that you're the hero, you get to make choices, because even if you're in a group and you're talking to a NPC, and they give you a choice - that choice is yours. Not your group; there are no group decisions in this game.
On going social
We really want players to meet in world, make it a little more organic, because meeting people in an interface isn't always much fun (though we do allow it). But we've public dungeons, where you go in, and so do other players - but they're not instances. They're actually in there with you.
Dungeons are a little harder than overground content, about one a half times more, so you're going to find yourself in trouble - and if you are in trouble and a player comes and helps you, or you see a player that needs help, even if you're not grouped, the game treats you if you were: it shares full experience, the rewards. You're encouraged to meet people, but you're not required to.
Class Customisation and the Everyman
You start out with the template, but you can deviate immensely... you can use any weapon you want, any armour you want. Which leads to lots of players have lots of different abilities. So when you group, you can choose what you want to do within that group.
On building the game world
Some of the parts of our game world haven't been seen since 1994, in Elder Scrolls Arena, so it means we have to choose how to represent the older things - that was 16-bit colour days, everything was flat... we have to make some artistic adjustments.