NMS Doubt Type 1: Why are people excited? This looks like a walking simulator, but, like, walking in space. Moonwalking simulator. (Think they know)
Response: Watch the trailers. Read the multiple threads addressing what you do.
NMS Doubt Type 2: I don't even know what this game is about. (Don't know)
Response: Watch the trailers. Read the multiple threads addressing this.
NMS Doubt Type 3: They are overpromising. The game looks like it is only going to be about flying around in a procedural universe, gathering resources, trading, exploring, shooting occasionally, developing faction status, and avoiding an omnipresent threat. (Thinks they promised more than they did)
Response: That's what you do in the game. Did they promise more?
NMS Doubt Type 4: I know what they are promising and I don't think this is something I will like.
Response: Okay.
NMS Doubt Type 5: They won't be able to do what they say they're going to do. (OP)
Response: We'll see.
NMS Doubt Type 6: Procedural games are always bad.
Response: A discussion!
1, 2, and 3 are infuriating because they're asking others to do their work for them. It's all there in the trailers. 4 is nice to know, but not super interesting. 5 is possible, but there is no way for us to know now. 6 is interesting.
A more interesting question is why this game gets so much doubt. I think it is a misinterpretation of the hype. It's getting attention because it is relatively novel, not because it will have universal appeal. The trailers recognize that. I think the focus on setting over gameplay does consumers right - you know what the focus is.
For example, the trailers for Red Dead showed mechanics of walking, riding, shooting, and resource gathering with cut scenes. It was set in the Old West. People who like those things in a game would like the game if well-executed.
Similarly, the trailers for NMS show resource gathering, exploring, walking, flying, and shooting. It is set in space and a particular brand of sci fi. If you don't like those things, you probably won't like the game even if well-executed.
So why do NMS trailers get the doubt? The former is largely GTA by horse and something we're used to doing and is pretty popular. The latter hasn't been done much lately (especially on console) and requires a different way of approaching the setting because of its vastness. The hype for NMS is, in my view, exaggerated largely because of that novelty, not because the game will be universally appealing.