Miles already lost his Uncle Aaron. Gwen lost her Peter, Peter loses Ben - the lesson that with great power there must also be great responsibility is already ingrained. Miles wasn't brave enough to act when he should have and Aaron died for it.
I don't think there's any value in telling the story that we've not only already seen, but that we know now has been repeated infinite times across the multiverse. I think it runs counter to the narrative at this point and would make a worse story if Miles DOESN'T show Spider-Man can be better. The Spider Society has resigned itself to letting people die because it's "supposed to happen." That doesn't sound like an ending Spider-Man would accept.
I can understand the other Spiders being resigned to the idea that it "has" to happen because it happened to all of them and they couldn't stop it, but the story here isn't about society changing Miles, it's about Miles - the anomaly - doing things differently. If it ends with everything being exactly the same, that's a disappointment.
Also, I think it cheapens the idea of "sacrifice" to insist it has to be a human life when Spider-Man is constantly sacrificing his time and well-being, his relationships, and his ambitions to save and help others. When you look at everything Peter Parker has given up or missed out on to help others, it's insulting to say that Spider-Man won't learn sacrifice unless Captain Stacy or his multiversal equivalent dies.
Beyond the Spider-Verse is going to be about confronting the reason behind the Canon events, that's my belief, and I can't wait.