While some will claim they want modelled, explorable interiors even without any associated gameplay, because of the "bond between pilot and ship" or some such thing -- and I do understand that -- I think that's a hard-core minority.
Most average schmoes who play computer games, including Elite, are not quite as focused on immersion at all costs and don't "bond" strongly to inanimate objects in non-existent spaces.
I would expect the vast, vast majority of players (who are mostly not on these forums) will be puzzled and frustrated by the presence of huge explorable spaces with nothing to do. Cue FDev's months of hard work being decried as "empty", "unfinished", "a mile wide and an inch deep" on Twitter, Reddit, and articles in the games press.
After a short while, the voices of the hard-core, now sated and starting to hunger again, will begin to join them: "when are we getting activities to do?", and given the more concrete experience of ship interiors, imaginations are given time to do their own backseat-developing, forming ingrained expectations that might different from the roadmap or from the possible, leading to less satisfaction and more griping if/when the features do come.
So since FDev will be getting harrangued about ship interiors either way, I think it makes complete sense to hold off on full interiors until they can be delivered close to feature complete.
This means not only modelling the interiors, it means designing new UI, coming up with lots of new mini-games, it means integrating any changes we make to our ship interiors with the ship simulation itself, it probably means boarding and interior combat and ship theft which leads to knock-on effects on balancing for the whole game on a scale that makes Fleet Carriers look like a triviality...
The more I think about it, the more it starts to look like a full-scale, standalone, full-focus update just on its own, and not something a 100-person team can easily chuck out alongside space legs, new planets and station interiors, even if they've had years to do all that.