So taking a quote from Deej "If you leave the tower you leave the protection of the Traveler" (or something along those lines). He could have said "last city" there instead of "tower" and that worries me. It seems like the world will be delineated as safe in the tower, and dangerous in the wilderness, with the city left out of the equation.
. . . I hope we can explore the city as well as the tower.

I'm pretty sure I recall a quote somewhere that said the city will be fully explorable.

So taking a quote from Deej "If you leave the tower you leave the protection of the Traveler" (or something along those lines). He could have said "last city" there instead of "tower" and that worries me. It seems like the world will be delineated as safe in the tower, and dangerous in the wilderness, with the city left out of the equation.
. . . I hope we can explore the city as well as the tower.

I think that's more in reference to the fact that the tower is will be where most of the social interaction is. The player spends the majority of their non-combat time in the tower is what I took it to mean.

It's official, the landscapes have been seeded to reward the explorer. (As if we thought that they wouldn't be.)

Nevertheless - DeeJ said it so it has been said.

DeeJ answers several questions from the Guardian Radio community regarding multiplayer, and reveals some details on multiplayer voice chat (voice may be optional with non-party players) however, always careful, DeeJ makes sure to tell us that Bungie reserves the right to change this before final release.

http://theguardiansofdestiny.com/#!/2013/06/16/guardian-radio-deej-interview-e3-2013/