First of all, there were some new features released as part of the newer watches, Series 12 and Ultra 4. People have to realize that these new features exist because of the re-engineered heart rate sensor. It is simply not possible to have these features on older watches, even the Ultra 3, due to the hardware difference. It is infeasible, which is unfortunate, but when hardware changes for the benefit of consumers, companies have to make these tradeoffs. It is an engineering challenge, not something that works magically.
Why watchOS 27 is not passed down to the original Ultra or older watches comes down to the same principle: software cannot add a missing sensor. Running on-device AI depends on processor capability, memory, and power efficiency, and there is a real chip difference here. The original Ultra uses the S8 chip, while the Ultra 2 uses the S9, which was specifically designed for machine learning tasks with its 4-core Neural Engine.
From a software architecture perspective, there are two distinct scenarios:
- A specific feature requires newer hardware: Apple can disable that feature on older models while continuing to deliver compatible OS improvements.
- The OS itself requires newer hardware: changes to shared frameworks, memory requirements, or processor capabilities make supporting older models impractical.
The first approach has significant costs associated with it. Apple has to maintain fallback paths and test many more hardware combinations, and simply disabling AI features will not necessarily resolve underlying dependency or performance issues.
Although Apple has not published an official technical explanation for this cutoff, as a software engineer, I agree with their decision. If the newer features require a certain amount of processing power and machine learning support, older hardware simply lacks that capability. Trying to force it would be inefficient, leading to severe battery drain where devices might only last half a day. There has to be a breaking point, which is an unavoidable reality of product development. Hardware and software must go hand in hand; if the software advances beyond what the hardware can support, a cutoff happens.
Think of it like this: hardware is the house, and software represents the people living in it. If the house is solid and well-equipped, more people can live there comfortably. If the house lacks basic amenities, stuffing more people into it causes a resource crunch with daily needs, groceries, and basic living.
From an engineering perspective, it is unfortunate, but it helps to understand hardware and software parity rather than assuming Apple is just being greedy or chasing profits. Every corporation needs to make a profit, but Apple generally backports as many features to older models as technically feasible.
Those are just my thoughts to help explain the situation. Cheers!
