The rumor mill speculates that Apple needed to ship something big and flashy to distract people from calling them out on their failure to deliver on the AI features promised (and previewed!) more than a year ago.

I've heard another take that is interesting and a clear departure from that never ending moaning: Like the ultra slim new iPhone that could be a step to validate the technical challenges to a foldable device, this change in UI is to prepare the user base for a complete change in the form factor, be it a glass slab or a greater focus on wearable (ala glasses).

They probably should have just eaten the AI non delivery instead of now having two major failures.