Gamewise and for an immersive experience i think a good dynamic campaign is needed. Luthier mentioned having drawn up a hefty design document for it, but like much else, it wasn't completed (or even started...
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Single missions let you experience the technical elements of the sim, but there is no real human edge to it. Scripted campaigns are better in that regard, but a really well done dynamic campaign can immerse you in something like the experience of a real pilot.
Don't know if we'll get it from the devs or whether it'll be 3rd party? Lowengrin maybe as you say...?