still thinking about how the concept of undead's AIs could have been explored even more. it makes so much sense for a morally bankrupt company like rhylink (who already doesn't understand the appeal of undead as a unit) to fund an AI version of undead using their old selves because all they see are numbers and the popularity of hellsing (and it's certainly what akira was expecting us to assume from the first half). they set up so much for the conflict to center around undead feeling useless in the face of technological progression, like all of adonis' comments about feeling unmotivated to improve his writing when he could just run it through an AI writer.
take rei's monologue in the final chapter about what the true strength of humans is -- that humans are alive. (and he's talking about himself, too -- he's a human, he's alive.) rei comes face to face with an AI version of himself that acts as his charismatic, godlike war-era self with none of the physical disability and limitation, something that can do anything and everything, and recognizes that it's not alive. not just because it's an AI -- rei was also not alive back then. rei was just like the AI, acting out a shallow personality, following a set pattern of behavior, not feeling any kind of human emotion or connection. like a living corpse pretending to be human. his "softness" in the modern era doesn't make him weak, but is rather his greatest strength. and now rei is loved just as he is, for being human.
i also think it would make the reveal of koga having written resurrection soul more impactful -- this is proof, flesh and blood, that AI is a shallow copy. every song koga writes is a labor of love (nightless world's lyrics make me incredibly emotional). rock 'n roll comes from deep within your soul, as koga would say! all the pain and love and character development undead went through over these past few years is sublimated into their music. AI would have been a fantastic vehicle to reaffirm what undead meant as a unit, especially in the wake of undead losing fans in !!-era and feeling directionless.