An even simpler explanation is that regular UI redesigns are an important tool for a device manufacturer to make the experience feel new or refreshed, and this

An even simpler explanation is that regular UI redesigns are an important tool for a device manufacturer to make the experience feel new or refreshed, and this novelty helps sell devices. Everyone reacts to the content of the redesign when it lands, but the fact that it happens should not be surprising. Usability issues only manifest after point of sale. Messaging/marketing happens after the work has been done (and can involve post-rationalization).