I'm not sure we'd see eye-to-eye on the multiplayer thing: where you obviously see scope for a multiplayer workaround to incorporate time distortion effects such as those we saw in FE2/FFE, I still think it would mean a lot of compromises to get ships with different grades of witchdrive to stay in sync, or identical ships if they jumped to different systems or had different payloads. I don't think it could work.
That said, I'm absolutely, 100% with you in disappointment that we lost the potential for an even richer, more complex flight model than we'd had in the previous games. One of the things I do love about ED is that the ships feel kind of heavy. Not the ridiculous artificial restrictions on turn rates that we're lumbered with because the game's trying to be a Spitfire simulator but in space (presumably the same reason we've no sensible instrumentation on board) -- I mean the fact that they just feel like big, heavy vehicles, and I imagine how this could have contributed to a 'proper' Elite 4. I imagine the physics of Martin Schweiger's Orbiter, but with 32nd century engines, frame shift capabilities, a star-spanning human civilisation, and a vast galaxy to explore (including the ability to land on planets with atmospheres!). And, like you, I think the concept of a speed limit in space, determined by engine power, is just... I don't even know what the best word is to describe it. "Retro", I think is probably kindest. Really, seriously, full-burn retro. As determinedly backward-looking as could be. "Arcadey" would be another way. "Maximum boost speed", for flip's sake...!
I've said it before -- I think even in this thread -- but I love this game. I play ED whenever I have chance. I certainly don't feel the anger towards it that you clearly do. For me, behind the enjoyment I still get from playing ED, there's just a general low-grade disappointment that they went for remaking Elite rather than advancing on FFE. But, my gods, what a beautiful thing a proper, modern, future-set space flight simulator could have been.