That's a very loaded question lol, for a low poly model, this isn't bad, I don't know what your programming experience is but even as someone who's getting experience myself now I would stay the hell away from MMO's especially if it's your first title. It's a major gamble at the best of times and I am somebody who has studied them a lot, you would be so much better off either doing a pure singleplayer game or a singleplayer game with multiplayer attached. You could even release a singleplayer game then add multiplayer on later, you don't need to go the MMO route at all and it would still be something people will want to play.
It depends on the gamer I think, but for me, as long as the artwork and UI looks relatively clean, I'm totally fine with low poly artwork, in fact these days I tend to prefer it because then I know my game isn't likely to run like garbage even on my mid-range desktop, some people even prefer 2D games specifically for that reason. Rimworld for example is just a bunch of 2D sprites cleverly programmed and that's a game that keeps doing incredibly well on the steam charts.
I realise I've just posted up a ton of information but I feel like you should take it from somebody who's done the research already. In terms of space sims, I would much rather see a nice singleplayer experience with optional multiplayer these days than another MMO that barely has any of the funding required to keep the servers up and running for hosting.
TLDR: I think any games developer in this day and age should stay the hell away from MMOs, the risk vs reward just isn't worth it and I haven't even gone into the potential legal liabilities a modern game dev has to worry about when it comes to multiplayer games.
