We know fdev want something tangible about stepping out of your ship. But I don't think fully "functional" ship interiors are a necessity, certainly not at EDO launch. Not for what they've shown so far anyway.
Ship interiors for the sole purpose of immersion isn't justifiable dev effort. It'd be an insane cost for such a niche payoff. But, if the effort also included seamlessly presenting the game functions in 1st person (ie, allowing us to get off our ship to walk about a settlement to the various areas to access missions, repairs, outfitting etc) then that'd be the ground work (pun intended) for perhaps thinking about the next step (pun also intended) which would be extending that seamless quality right to the cockpit (even if the route was limited for now).
More so if boarding ships became a feature of game play. Which, if we take the majority of science fiction space media (books, stories, films and shows) as reference material, almost everything includes some form of boarding another ship, both hostile and non hostile.
I'd say ship interiors will be worth it then. And only then.
Happy just to be able to get out, walk into buildings and interact with npcs right now though. It'll be a good start, even if it's only on planets.