I think they got caught with their pants down when everybody started doing AI and they were like “hey, we have this cool VR headset”. Otherwise they would’ve at least prepared the regular iPhone 15 (6 GB) to be ready for Apple Intelligence. Every (Apple Silicon) device with 8 GB or more get Apple Intelligence, so M1 iPads from 2021 get it as well for example, even though the M1’s NPU is much weaker than some of the NPUs in unsupported devices with less RAM.
They are launching their AI (or at least everything under the “Apple Intelligence” umbrella) with iOS 18.1 which won’t even release with the launch of the new iPhones, and it’ll be US only (or at least English only) with several of the features announced at WWDC still missing/coming later and it’s unclear how they proceed in the EU.