and it was made out that we could explore them on foot if we wanted to - miles of roads and corridors and walkways, etc.
Yeah, kind of. As Mole's screenshots show, there are some nice cities, and some you can walk around lots of corridors and walkways.
But you know how some people say "But ED's planets are boring, just the same boring terrain with nothing to do there", well, its kind of just the same, but replace terrain with corridors.
But, if you know where to go, on which planet, and in which city, and follow miles of corridor, i know of one NPC who gives missions.
There is also a large disconnect between what CIG show off and what is avialable and a disconnect between what backers will say as well (backers have this strange habit of talking about future things as though they already exist... it would be like talking about walking around your ship in ED right now, even though it doesn't exist... yet).
Of course, take what most of us are saying with a pinch of salt, because we have our biases as well, and might present some things in a worse light than they actually are.