Some may dismiss things like this as trivial, and that's fine, however, for me it does really break immersion* and takes me out of the game. I'm out exploring far from the bubble and in the "imma explor!" mode having fun, then I get buzzed by another ship, that I know just spawned in cos I'm there. It turns the experience back into a game, if you get what I mean. Of course it is a game, but that doesn't mean I don't want the experience to make some sense. I like going full kid mode and discussing things in-game like they're real, it's fun lol. Some might say I like to immerse myself in the experience... There's something about that feeling of being truly out in the black, all alone that I can imagine the more serious explorers (I'm not one of them) absolutely adore about the game.
* Yes, immersion is important, I really like getting into that head-space when playing game like this. Perhaps less so for the "line them up" pew pew at times, but when I'm out where no one has gone before, I want to feel it, as much as that's possible in a game.
I can't imagine it's a tricky thing to make encountering another ship far outside of the bubble a very rare thing. Hell, maybe that's a role for other players to fill. If you encounter another player out in the deep, it'd be an event. Encountering the umpteenth spawned in NPC though. Yawn.
Now, if I were to encounter an NPC Fleet Carrier in a distant system that's home to a serious mining operation due to crazy rich local resources, that might be cool. However, again, that's a role filled by Players. I've DONE that. I've taken the Carrier to a distant system I've found and spent days mining. I'd say all alone, but, upon entering the rings around [censored] in the [censored] system, I'd have to wait out the Pirates that spawn in. I'd arrive, they'd pop in and either fly off or scan my empty ship and fly off.
So, yeah, little details like this are important if I'm to be "lost" in the game, which is exactly what I want. A little break from reality to play space ships.