I think originally being made as a sort-of DLC that got upgraded to a standalone title explains a lot about it and how little it diverged from the original. When you get a sequel, I imagine there's a lot of thoughts in regards to what they changed and what they didn't change, if mechanics were streamlined, made better or worse, though invariably - or almost always at least - the game at least feels bigger (sometimes for the worst)
In this case its just...slightly different? You get a named PC with her own voice, which frankly, is a major negative point for me, as well as more voiced interactions and even cutscenes, but the gameplay loop is largely the same, as are most of the tools you build, resources you collect, and vehicles you research. With a few different details sprinkled here and there - there are new predators and fauna, instead of SeaGlide you get a SeaTruck - this feels more like starting a new save file with added mods than a different game.
While that's not a dealbreaker for a lot of games, when you're playing a survival builder where the joy comes entirely from, well, building and surviving, entering a world where you're researching the same items again, engaging in the same gameplay loop again, building the same base again its just very unfulfilling. And it isn't bigger.
Not a terrible title, or even a bad one, but a very odd retread.