I thought the engine modes in ED were quite realistic - little different than Star Trek's 3 engine modes really. In terms of "flying around in space" I think that game got the actual travelling around (while maintaining a sense of scale) the best yet, it gave you the sense of enormous distance between stars and planets, but was gamified enough and hands-on enough to be not boring, and didn't take too long to be boring either (and you're always going to want to be able to skip time for really long interstellar journeys anyway).
ProcGen was done very well by the original Elite, although that was at a much more primitive level where it could be done convincingly within the tech constraints and abstraction parameters then. It's likely that procedural generation going forward (which has the much harder job of filling in entire planets' worth of detail) needs to work in tandem with AI to make it work properly (which is why I say this type of game hasn't really been made yet).
What you're going to need is a "Potemkin Universe," so it's designed around you and your choices, as a DM would, but without making it feel subjectively like it's designed around you and your choices, in a way that leads you through an intended story. And I think that can only be done by an AI that's aware of a designed main story and some designed ancillary set pieces, which then kind of surreptitiously guides you and the ProcGen both, towards it. Basically the original idea for Daggerfall, but magnified x100.
I don't see why good trash encounter design can't be procedurally-generated with AI and ProcGen working in tandem too. One might think, "Well then, what's left for the actual developers to design?" Still plenty: the basic art design, the story and set pieces, the lore flavour. Everything does still have to be "seeded" by human design and have a handmade flavour. At its core, it's still got to be some humans entertaining other humans, humans telling other humans stories around a campfire.
