Basically, I didn't want to over complicate things. I've found that it's ok to do that in a solo story, but the moment you start doing that in RP it tends to go to shit. Pardon the language. But..... it's oh so true. I've seen it happen and it tends to bring failure. So, I've learned to pick and choose and oust things even if you REALLY want to include it or would under different circumstances. It's like the time thing. I'd normally include that. But, here, it would be so ridiculous to even attempt it. And with the whole gravity and atmosphere thing? I like it to a degree, but I think it could get a bit overwhelming and cumbersome. Solo or 1x1 RPs it could probably work fine. But with groups? Probably not so much. Again, just talking from experience. Too many fine details weights it down and then you end up with stalls and eventually the thing dies.
As for ship restrictions? I wouldn't go too insane. Like some of the SW ships are a bit grandiose. But I think if we keep ships on the Firefly/Serenity level, we should be more than fine. And some of the smaller ships in SW should be fine too. Again, I'm pulling from SW movie verse (I know Nihil knows A TON about SWverse of the ALL AROUND kind, lol).
Hope this insight helps.