I think the word "perspective" is exactly the right word with which to frame this player ship interiors discussion.
The player ship interface perspective matters because Star Trek, as drama, isn't just about action -- it's about characters.
In drama, character supplies meaning. Action is cool, but for action to have any meaning, it has to happen to characters and characters must be seen to react to it. Ultimately action has to be about people because it's the choices people make that communicate what's really important in this all-too-brief existence of ours.
Is it possible to have "characters" if you interact with them from an outside-the-ship perspective? Sort of -- you could show representations of their faces in a GUI window that pops up while you're steering the ship.
But is that as effective for showing the inner struggle (the meaning) of how we face hard situations? Is seeing a picture of a person as gripping as seeing the whole person from the perspective we've always seen Trek characters, that being inside the ship with those interesting people?
I don't think so. Seeing a picture of a thing is not as powerful as having the feeling of being in the same place as the thing itself. It feels less immediate, less real; it conveys less meaning. It is, in a word, less "immersive."
Immersiveness doesn't matter to everyone. And that's fine. Having a third-person exterior interface is great. I fully support implementing a third-person outside-the-ship interface for player ships.
But whether such an interface for player ships should exist isn't the question. Whether it should be the only interface is the question, because immersiveness matters greatly to some prospective subscribers to a Star Trek MMORPG. For a lot of people, story (the character motivations that drive the action) is necessary to make the action of a game fun. Without implementing a gameplay interface that maximizes the immersiveness of the action, telling a good story about interesting characters gets harder.
A third-person, outside-the-ship perspective doesn't maximize immersiveness.
A first-person, inside-the-ship perspective doesn't maximize immersiveness, either... but it comes a lot closer to doing so than an exterior perspective does.
By emulating all the Star Trek TV shows and movies that put the audience right there in the room with the characters, Star Trek Online has a chance to be a more broadly satisfying and therefore more successful game. Yes, the Star Trek shows included cutaways to exteriors to show some action... but the camera never, ever stayed there. It went back inside the ship to show us the characters, because having a first-hand experience of their reactions gives the action much more punch for the viewer.
It can and should do the same for Star Trek Online players, and for the same reason.
To the argument that "hubs will provide this first-person experience," I respond that if that experience is so good to have, why restrict it to hubs? Letting immersive gameplay happen only on hubs would be to miss an important opportunity to improve the gameplay for the many players who will be spending most of their game time aboard player ships. Considering the likely numbers of such players at any moment in time, player ships need to have features that appeal to a wide variety of gamers. That justifies spending a lot of development time on offering different kinds of gameplay (combat, exploration/science, diplomacy) as well as on making each kind of gameplay especially appealing.
Combat-focused players will have plenty of that; I don't think anybody believes that whoever finally completes a Star Trek MMORPG is going to skimp on starships unleashing electric death at each other. Offering an interface that supports fast-paced tactical fun makes sense. But what about the gamers who care more about playing with cool advanced technology and interacting with interesting characters? Why should they be stuck with only a utilitarian third-person external interface because that's considered best for tactical (combat) gameplay? If a first-person interior interface brings in more cash from the immersion-focused gamers because that's more responsive to their gameplay interests, and if there are enough such gamers, then why is it necessary to argue against also providing this interface for them?
Would having only exterior views for space-based gameplay "ruin" Star Trek Online as a Star Trek MMORPG? I don't think so, not entirely. It would, IMO, just make ST:O less satisfying for a financially significant number of potential subscribers -- enough, I think, to make implementing an interior interface for player ships worth the development cost.
So, to summarize: An interior, "you are there" interface for player ship gameplay is a more emotionally engaging way of representing characters than an exterior, "viewscreen" interface. Showing engaging characters will attract more of the subscribers (including ST fans) who prefer a story-driven play experience. If there are enough such gamers (and I'm convinced there are), they will more than subsidize the development costs of providing an interior gameplay interface.
So I think the reasons for implementing an interior gameplay interface for player ships outweigh the reasons given for deliberately not including such an interface. I therefore hope Star Trek Online's developer will choose to offer both an interior and exterior interface for player ships.