Stellar Blade's director admits 'the narrative was lacking', but wants to make up for it in the sequel
Development costs and unfamiliarity with narrative-driven games held back Stellar Blade's story, according to Kim Hyung Tae.

Stellar Blade director Kim Hyung Tae has admitted that the game was a little lacking in the story department, citing costs and a lack of developers in Korea who are familiar with more narrative-driven games.
In a machine-translated interview with ThisIsGame, Kim admitted that crafting the story proved to be pretty challenging for Shift Up. "The core gameplay system was completed relatively early on, but the thing that held us back the most was the cutscenes," he said, agreeing that "the narrative was lacking."
"In an action game with a narrative, cutscenes play a very important role in storytelling. It's hard to tell all the narrative through action alone, so you have to take the [story] through cutscenes, and initially we had a lot of setup and a lot of things we wanted to do in cutscenes."
Unfortunately, it seems as though Shift Up was gated by how much cutscenes cost to create, and ultimately several worldbuilding and narrative beats were canned as a result. But what kind of lore nuggets were cut, I hear you asking? Well, Kim doesn't really go into detail about any of that, but he did reveal that one of the plot points was supposed to explain why Eve owns a million different outfits that she can change into on the fly.
Now as a silly lore sicko, I would have absolutely loved a canon reason behind all of Eve's different Nano Suits. I can understand why it was axed in favour of, y'know, actually shipping the game out, but I'm still a little bit gutted I've been robbed of the inevitably bizarre worldbuilding logic.
Curiously, Kim also cites the Korean game development talent pool as another reason behind a weak story, saying that the country isn't exactly plush with folk who are well versed in narrative-driven games right now.
I do find that reason interesting, as Shift Up's other game, Nikke: Goddess of Victory, has a pretty solid story going on. Granted it doesn't have to go balls to the wall with cinematic cutscenes since most of the narrative is fed through 2D sprites and text boxes, but the stuff that's there has kept me almost entirely enthralled across its almost 40 chapters. Think Nier: Automata's "come for the thighs, stay for the cries" energy.
I would have to agree with Kim, though, that Stellar Blade's story is pretty weak. It doesn't have the level of worldbuilding I've come to expect from Shift Up, and even the multitude of text-based lore drops throughout the world ultimately all boil down to some variant of 'I'm going to die' or something related to the ever-looming Mother Sphere.
Kim says he doesn't want to do any tampering with it for now, saying "I'm cautious about trying to make up for it now because it might conflict with the story that users have already accepted. However, if we are given the opportunity to make the next one, I think we will be able to present it with a rich enough narrative."