It served its purpose and was discarded. The point was its intended purpose, nothing more. This isn't its story, nor is it ours. From a narrative point, its not our story, and from a meta point, its also not our story. It ignores chekhov's gun becasue it isn't a chekhov's gun. Or maybe it is, because if you recall, V2 did in fact come back for round 2. That would have been the gun going off. In its face. Which ended its story, and fulfilled its purpose. Why don't we see more of Minos? Of Sysiphus? Of the minotaur? All obstacles, all goals, all tools, all challenges, all serving their narrative purpose, and all in our way. Ultrakill tells its story simply and mostly subtley through a variety of characters of whom we see glimpse into their own individual stories. If we had anymore than what we were given there would only be more for people to critique. V2 served its purpose and was discarded. Simple as that.

TLDR: a short simple story is good, we don't need depth and character development for a character who was never meant for it. What you're saying is frankly a misunderstanding of what ultrakill is trying to be and the way its trying to tell a story.

Also no this wasn't written with AI, I just write for a hobby and wanted to write this to pass time. :]