The downside of such play is that you can be at the mercy of fate....have the wrong crew members offline for some reason, and your game experience suffers. There's a reason MMOs tend to move away from large groups and are trying to introduce a more flexible approach.
I personally prefer multiplayer that is optional....not the main focus of the game. Sea of Thieves looks interesting, but the multiplayer multicrew approach doesn't really appeal to me and has turned what would otherwise be a certain purchase into a "maybe".,
Having said that, it is great to see Rare doing something other than Kinetc game again, and it would be nice to see some of the old franchises make a come back. Perfect Dark for example, or Jet Force Gemini or even Conker. Maybe even a new Sabreman game - maybe they could even release Mire Mare
But yeah - to me, multiplayer games bring as many problems with them as they do potential and for all that players like multiplayer, I think the recent failures of certain MP only games demonstrate the folly (my opinion) of such an approach. A strong single player campaign frees a game from the necessity of embracing and creating a strong multiplayer community, and address the flaws of multiplayer systems just as a strong multiplayer game leverages that community to enhance the overall gaming experience.
Whether I buy Sea of Thieves or not depends on how good the single player element is. As for whether any of its systems can be translated to ED....in principle, sure. In practise, there's a lot more to gaming systems and what works in one game does not necessarily translate well to another. I'd have preferred a different iteration of multicrew in ED myself - my concept was to provide each ship with new multicrew modules that could be attached to specific hardpoints, with each module tailored to a specific task and requiring a dedicated crew member to operate, ensuring that gameplay could be tailored around the various needs, with new module specific gameplay and ensure that such gameplay ADDED to a ships capabilities rather than replaced it - but we got what we got.
Whether any of the ideas or concepts are worthwhile adapting to ED is something that can only really be determined in play after seeing how those systems work in a live environment.