The “learning how to play“ phase of the game is somewhat harsh. It kinda wants to give you a cultural shock and lost feeling.
That scares away a lot of players.
Secondly, the core gameplay is focused on decisions for survival, and the old school text adventure style alien interactions play a bigger part than brute force exploration, which doesn't meet the expectations of some players.
The achievements do not necessarily come in while “playing normal“. some are really hard, some are just the collecting/completionist type of things. In one run, you can see at max 20% of the available content.
the meta gain are not different characters or upgrades or so. the meta gain is simply knowledge. the more you know, the more you can explore.

So, overall i'd say the game is a very niche game, with hard achievements. Those which do not enjoy the replay value, be it with different seeds to see something new, or with the same seed to fully explore it, stop after reaching earth for the first time.

hour wise.... phew. for 100%...
Afaik, it might take you 30-60 hours or so until you've seen all the major quests and races. with the wiki you can cut down on that. from there, i'd say it comes down to skill and seed: master one route on one seed, then you can do the achievements in that seed in rogue mode like flipping every alien race off, or not repairing the ship or so. that then leaves the collections/see everything. with the skill aquired, you should be able to explore extensively in story mode (i've seen players extend the ~20-40 ingame day planned playtime to like ~600 despite the ship just falling apart faster)

one run can take initially ~6 hours, if you know the seed, that can go down to ~2. if you are optimizing it for time, players have gotten it done to 25 minutes for the seed Speedrun, but that isn't helpful for the achievements i'd guess.