They only have external damage modelling for the Anaconda, so you can probably imagine how likely it is they'd do different interiors for different ships.
Good point... it does show they have form throughout the game's history - the mining revamp shows they can if they want to, but unfortunately there's way too many half-baked/semi-finished aspects and placeholders in the game... I wonder if their theme park IPs suffer from the same problem or whether this is specific to Elite. Maybe they outsource a lot of the content (the 4.0 UI revamp certainly gives me that vibe).
That is same with Odyssey DLC or any paint job: Added value may justify an extra price. If one doesn't see the value, they don't have to buy it. Interiors may have little potential to 'win the game'

My argument against 'whales' is that this term is a hyperbole: How much did we spend for our gaming rigs? Other games? A cup of cappuccino? Would a
very casual player miss anything if they hadn't the Interiors DLC? N.b. I am considering myself to be a casual player because I spend between 3-9 hours per week in ED.
I spent north of 600 Euros on Elite. Is that sufficient? Too much? Not enough? Do I qualify as a whale (personally I'd say yes, but maybe only SC level spending does to some people?).
Either way, I tend to answer that question by looking at what other games (i.e. the competition in terms of products vying for my entertainment time & budget) offer... and on that basis Elite isn't a good deal in pure money terms, even if I take hours played into account (and I can say for sure that a sizeable chunk of the 5k hours in Elite were not particularly fun, though the end often justified the means).
Elite is often sold at heavy discounts (or even given out for free), while other games still sell at full fat prices. That's really on Frontier though... I'd prefer if they kept the base game and DLC pricing stable, while including at least some of the cosmetics in the price for free instead of making such an industry out of it. They decided otherwise and it is what it is.
You could look at it from another perspective. Are people that scored the game from the bargain bin sale more likely to dump dozens if not hundreds of notes for often questionable-quality cosmetics? I'm not talking about enthusiasts like you or me, but your regular play-game-for-20-hours-then-drop-it types.
That is a fair point. But would it really make sense from a commercial perspective (yes, FDev needs to make money to pay their employees, etc.) to develop a ship interior for e.g. the Asp Scout? (Sorry players, don't beat me, it is an example). FDev has the telemetry to make a good guess which ships may be the most popular not only in terms of flight time but also how much players are spending on their respective ship kits and paint jobs.
Hehe, poor Scout, good example. Both for your argument, but also my counter-argument... They could maybe make it less rubbish by overhauling its characteristics? It's their game, there's nothing keeping them from changing it, and they would also sell more cosmetics for it as I'm sure people who are/were willing to fly other beauties-in-the-eyes-of-their-beholders would do the same with the Scout if it
had any redeeming features at all.
I agree I want to have ship interiors with added game play - not just for the sake of having some walkable cabins and corridors.
You know, I really am split on this need for gameplay associated to interiors. I get why people would want it... but...
In X4, there's no real gameplay to walkable ship interiors - well, there is, but it's pretty light touch, mostly story driven (i.e. meet xyz on bridge or crew quarters to talk to), but it adds so much to the scale and character of each ship, even if there are only few rooms available (although ships like the Astrid also exist).
It's just nice to be able to walk towards the ship, see your pilot through the canopy, climb up the ladder/ramp, and walk towards the pilot chair to relief said pilot from their duty (or command them to lift off). It really gives me the sense of
physically stepping into a spaceship. Despite some jank at times.
I still find it fun and immersive, and even after 1,200 hours in the game don't usually short-cut (button combo to skip to ship cockpit is available) unless I'm in a hurry, or
eventually tire of it so it's a good an necessary option to have still.
My skepticism around Elite interiors comes from how FC interiors were designed - there's just one layout, built from recycled Odyssey assets, and still glitches out now and then. I wouldn't be against it per se but I don't see Frontier having the ability to pull it off properly, with the level of attention to detail that it clearly deserves.