Those games have exhibited some sense of greater purpose in their videos at this point before their release. When they haven't, people have questions about what it is that you do in them. It's not 'concern' or anything someone will likely end up painting it as. I've seen other vids and heard the commentary about the main objective of heading toward the center of the universe, but what else goes on besides avoiding/fighting the sentinels or galactic police while taking resources from planets and exchanging that for currency to upgrade your ship? Yes, 'discovering' planets and their varying species of procedurally generated flora/fauna is there, but what else? What is it that makes up the experience after the first hours of finding your footing?
Minecraft had the built-in hook of building and crafting as a necessity and main activity in addition to exploration and combat with the monsters. It also has a loose goal in dealing with hidden strongholds and looting them for rare items. Unless I'm missing something, they haven't yet shown off or discussed the central pillar of what motivates the player in between the point of going to the center of the universe and any moment before that once you've attained interstellar travel in NMS. With MC, there's simply the creative element of building logic-based mechanisms and sourcing their constituent materials while socializing and collaborating and fostering other life as well as building structures that you want to or need to in order to survive or make your area more hospitable. Where there's no one else to play with or against in NMS for the first stretch of its released life, what is it that keeps you going in the meantime? I'm asking the same question many are for a title that is probably due by end of year.