All ships have been designed with the interiors in mind and for future gameplay opportunities. Such as walking inside ships, space stations, spaceports, other vehicles, cargo loading and storage, boarding, damage models etc. Elite Dangerous is structured in a way that allows all of these elements to be added. Currently only the cockpits of all flyable ships are accessible.
David Braben explained in the Elite: Dangerous Development Plan video on Dec 14, 2012:
"We're designing all the ships with the interiors in mind. How the cargo is unloaded all of that sort of thing, how damage occurs. That's because another thing we are doing is, again down the line, is that you will be able to walk around inside your ship. You'll be able to get out of your ship, walk around inside space stations, other vehicles. All of that sort of thing. We've shown the damage on the ship, the damage models. Imagine looking at that from inside the ship outwards seeing your cargo fly out into space, seeing the flames trying to fight them. All of those things that we plan with time, they won't be at the first release, because we want to do them right, we want to do them well. All of these will be done as updates. The game has to be structured in a way to allow it from the start. So we're designing the ships so that they work that way and so that when we come to do it, it's not a problem."
"When we come to show all of these elements, walking around the ship, walking into other people's ships, potentially stealing them, we have got in mind all of the things, all of the really rich gameplay that entails and it's, you know, going back to what I was saying right at the start of this Kickstarter, what is the game I want to play? This is the game I want to play, because actually in many ways it doesn't feel like a game. It feels like a world that I'm being brought into and with each of these subsequent updates we expect that world will get richer and richer and more and more of the things that we talk about will be there. You will be able to walk around in a spaceport, you will be able to see gold being loaded into someone else's ship, you will be able to sneak in and hide amongst the cargo. All of those things are phenomenal gameplay opportunities, where that ship might actually be, the ship of another player. So all of these things I think we need to do right."