There is obviously the immersion factor, which I would argue is critical for a game like Elite.
But ship interiors also have potential for interesting gameplay, and particularly with multicrew.
With Odyssey introducing the APEX travel agency, there's going to be a good number of commanders going without ships, and probably quite a few alt accounts of long time players where no ship is ever to be purchased. This would make it likelier that features developed for multicrew interior gameplay would be frequently utilised.
The catch is that interior gameplay must be as enjoyable for the crew as it is for the ship owner, or perhaps more so.
There'd need to be more roles, and they'd need to be more flexible. For example, the ship owner should be allowed to let another commander pilot the ship, and gunner roles should be able to be split by individual weapons or weapon groups. With walking around interiors being a thing though, there will be crew roles that don't require a seat in the cockpit.
I think the gameplay would be centered around ship boarding mechanics, so you'd have defenders at different relevant locations if you're being boarded, and you'd have attackers geared for certain offensive goals when trying to board another ship. You could have commanders run to the cargo hold to counteract hatch-breaking attempts, or prevent cargo being stolen. You can have defenders in the cockpit to prevent the ship being stolen. You could have a "base defense" role for deploying things like auto/manual laser turrets, force fields, and other traps, with the option for manually controlling turrets, turning force fields on and off, and locking areas of the ship to trap invaders.
Of course, there'd need to be some worthwhile rewards system for crew members, maybe with any successful activity being considered a completed mission, and depending on where you are and faction affiliations etc, there'd be a reward to collect at the nearest or relevant port.
I could go on, and there will definitely be problems to solve with the above quick suggestions, but the point is there is potential. For me personally, just being able to walk around my ship (or even just the cockpit) would tide me over while the devs take their sweet time coming up with some interior gameplay mechanics.