Wouldn't it be a really bad projection-system if it couldn't appear like it was really there, outside your cockpit? I never had a problem with that, since technology in thousand years probably advances quite a bit over what's possible today.
That's arguably true, but it's subjective. Part of the problem with the lines appearing "at the same distance" as the planets, which I didn't elaborate upon but will now that it's been raised, is that the virtual distance itself is something that the brain has to intuit from other visual cues and from the "knowledge" that one is sitting in a spacecraft looking out at the infinite beyond. If the planets give the illusion of being tens of light-seconds away and the lines are the same distance as the planets, this isn't a problem. But if the
lines suddenly appear to be too close, and the
planets are the same distance, there's a disconnect and all of a sudden you're looking at a 3D virtual space of arbitrary size and not an entire galaxy.
Like I said, it's hard to explain unless you see it yourself, and not everyone sees it. This is why I'm fine with the cockpit holograms and the on-helmet projections, because they remain within the cockpit and move believably with the pilot's head. But I never felt as though the orbit lines were as convincing. They have the tendency to make the whole space outside the cockpit feel that little more artificial.
One of the joys of
ED for me is that it can be utterly convincing for long stretches of time. When I play games like
Tomb Raider or
Assassin's Creed, or simulators like
FSX, or even other first-person games like the
Call Of Duty series, no matter how beautifully rendered the visuals are I sometimes find my perception flipping between absolute immersion in the virtual world and sudden bursts of "matrix vision" where the world breaks down and I can "see" a construct of geometric shapes, bitmaps and bounding boxes. The frequency and duration vary but it's always there, a nagging reminder of the artificiality of the game world. It never really goes away.
By contrast,
ED is the
single most convincing simulation of a fictional world that I've experienced in 35 years of gaming. Maybe it helps that I'm such an SF nut, and maybe the fact that
ED "only" has to render mostly black space with a few round things in it. Or perhaps it's because I know
ED is portraying as realistic a vision of the actual galaxy as current technology permits. All I know is that for most of my gameplay sessions it remains an amazingly believable experience. When I look at that cluster of wiring running down my Diamondback's B-pillar, it's as though I'm looking at something three feet away. And when I glance just to the right or left of it at the stars, it's as though I'm looking at things hundreds or thousands of light years away. Even the lack of forced focus effects doesn't break the illusion for me. It's a rather incredible achievement.
The orbit lines, when I turn them on, break that illusion. They turn the infinite cosmos into a finite box of stuff, into which a smaller box of stuff (the cockpit) is placed. It's a shame, because they are unquestionably useful, but at the end of the day I have to go with what feels right.
Disclaimer: as I revealed in early posts about 3D, VR etc., I don't have stereo depth perception. One of my eyes is considerably weaker than the other and provides only marginal peripheral vision. Almost all of my day-to-day distance judgement, whether for nearby or distant objects, is done using parallax rather than stereoscopy. I don't see the real world in quite the same way most people do, which may have a considerable effect on my perception of virtual worlds. So all of the above may well be unique to me, or at least to me and others with effective monocular vision. Incidentally this is also the reason I stick with TrackIR and haven't tried Oculus Rift; depending on whether or not it works with my eyes it could be amazing, or crushingly disappointing, and I'm not ready for that level of disappointment. No 3D cinema or TV technology has ever worked for me (how could it?) which doesn't bode well.
TL;DR: Ultimately
ED feels
astonishingly real for me with the lines off, much less so with them on. So of course they stay off! YMMV.