Combat: Sure, but why bother with ship interiors? You could have much more variety and leeway for creating an arena actually designed for combat by doing it on a planet or inside a station, instead.
Diplomacy: Same thing.
Maintenance: Simultaneously boring and impractical, given the raw size of our ships. Even worse, if you can manually repair your ship, it makes players feel pressured to do so, so they can fill the AFMU slot with something else.
Decontamination: Same thing.
Base building: Well, that would be cool, I'll admit. But doesn't have much to do with ship interiors.
Engineering: Just what we need, more engineering. Plus there's the issue of making it interesting.
Passenger Gameplay: Why do we need to get into the passenger section for this?
Crew management: What crew?
Smuggling: I'm 100% for smuggling being made better, but how would ship interiors facilitate this?
Value isn't a matter of opinion, it's a real, calculable thing. You can anticipate exactly how much time the average player will spend using a particular element, and thereby calculate how much dev time it's efficient to spend making it. It wouldn't make sense to fully design the interior of a gun most people would ignore, for example.
So in this case, yes, absolutes absolutely do work.