Hmmm. Well, ultimately, it boils down to this - hunting NPCs is bland, easy and just repetitive / boring after a short while. There's absolutely no reason to cooperate in NPC hunting because your ability to farm them is limited by their spawn rate rather then actual danger in engaging them.
If it is again by design that NPCs are a pushover ("we expect even a newbie player to be more of a challenge") and that PvP is discouraged, then basically the only non-predictable, challenging and engaging activity (well, short of sightseeing the milky way which is not so predictable, quite engaging, and has a competitive touch to it - my favourite activity) is discouraged and de-incentivized.
Of course open mode should not be about wanton murder (and safe systems should be safe systems) but the game is sold under pretense of being a MMO set in a cutthroat galaxy, and neither is the game a MMO, nor is the galaxy a cutthroat one without PvP. I think the mantra "let everyone play the way they like" isn't sound design. Aside from exploration, it's kind of a themepark / grindville to get the next best ship / outfit to do more of the same except at a faster pace and with cooler visuals. This is the gist of the negative Steam reviews; the gist of the positive ones is "it has exploration of the milky way and flying a spaceship is really fun" which is also absolutely true. I think we gamers are expecting more these days in general - what was good for a single player game >10 years ago just doesn't really sustain people's interest all that much now.