Because it’s tradition …
Yes: New MacBook, new MacBook Pro, 10″ iPad Pro, new MacOS, new iOS, new WatchOS, new tvOS, HealthKit expansion, Home expansion.
No: New Mac Pro, new iMac, new phone, new watch, anything with “Air” in the name.
Maybe: Siri-based home assistant. If this drops it’s going to be more of a “home audio device that has Siri” than a “Siri device with home audio” … Sonos is the target, not Alexa.