In slight fairness:
Ability to opt out: Perhaps most importantly, users can opt-in for Apple Intelligence features, which will be introduced as beta versions as Apple works to improve its AI capabilities over time.
As with so many privacy things, of course, the issue is less what I may do on an Apple product than what someone I'm connected with does. If I get an iPhone (which I'm not planning on), I can tell Siri not to use AI on my messages, but I can't tell Siri on someone else's phone to ignore messages I send there.
(All that said, the entire decision here seems to be surprisingly at odds with how Apple usually does things; licensing ChatGPT feels like an acknowledgment they they're nowhere near any of Meta/MS/Google here. Last time I can recall Apple doing something like this was when they licensed Internet Explorer back in '97, and it took five years before they finally released Safari.)