I'm one of the few people who loved this game at launch, and I've never really stopped playing it, though I've had a few breaks now and then. It just seems to be endlessly intriguing for me. (I originally played on PS4 for a long time before upgrading to PC, so I have many more hours than are logged here!)
I think it's important to be clear about what kind of game NMS is. It's not really a multiplayer game, though it has multiplayer. It's not really story-driven, though it has a story. It's not really missions-based, though it has missions. It's not really factions-based, though it has factions. It's fundamentally about two key things: exploring, and building. You don't have to enjoy both of these to enjoy this game. I have very little interest in building. But you really do have to enjoy at least one of them. In this game, it's all about the journey. The missions, including those in the main stories, aren't particularly exciting. Most are basically fetch quests. What they're really for is to get you out there, into the extraordinary universe in which this game is set, and journeying through it. Many players aren't interested in that, and lose interest because they feel there's no point to any of the activities in the game. That's understandable, perhaps. But if you're the kind of person who is interested in exploring a vast universe, and in simply appreciating what they see along the way, it never really gets old.
This is despite the obvious flaws to the procedural generation system. People often say that there's not much real variety, and after a little while you've seen all the combinations that are possible. This isn't really true. Some things are very rare, and even after playing for a long time there are always new things, and certainly new combinations, to be seen (quite apart from the fact that the developers keep adding new stuff). There are of course also mods that can add new combinations, if you want them, but honestly the generation is varied and complex enough now to remain interesting for a long time.
The sheer scale of the game is both daunting and wonderful. The starting galaxy, Euclid, where most players spend most of their time, and which has by far the highest population of players and the most discovered systems, is still about 99% unexplored. Some time ago I was playing in one of the expeditions, which are timed events set in particular regions of the universe. All of the systems in these areas get discovered very quickly, of course, because so many people are playing there. I had an Explorer ship with a maxed out hyperdrive and decided just to leave the area and keep on jumping. After a couple of jumps, I was in unexplored space. I kept on jumping, and jumping, and jumping, further into unexplored space. This was, to repeat, in Euclid, starting from a densely explored expedition region. The way the music swelled as I zoomed further into the galaxy map each time, the way I kept landing in unexplored systems, the way every one had a subtly different space station full of NPCs - I was really hit, for the first time, by the utter vastness of what Hello Games had created. It was almost an existential moment.
NMS is the "forever game" for me. It's not perfect, certainly. I'd be happier if Hello Games had spent more time developing the aspects of the game I love (planetary variety and depth) and less time on the ones i'm not interested in (multiplayer, base building, combat), but I'm also aware that if they'd done that they probably wouldn't have the player base they do now, or the ability to keep on improving the game. In any case it's the closest thing that exists, or probably will exist, to my perfect game. Oh, and it's absolutely phenomenal in VR - one of those rare things, a conversion from flatscreen that feels like it was designed for VR from the ground up. The fact that you can play the same saved game in flatscreen or VR as you like just adds to the versatility. It goes very well with Natural Locomotion - I've spent many hours "running" in this game!