For the record, I would have liked the time between the delisting of 32-bit apps in the store and the dropping of 32-bit support from the OS to have been significantly greater. Ideally, 32-bit apps would have been delisted around release of iOS 10 (but still available for redownload if previously purchased), really lighting a fire under developers' asses well in advance (despite Apple asking developers to move to 64-bit in 2013) and preventing users from buying software that wouldn't last another year.
Are their even any iOS devices with more than 4GB of RAM? I don't see why an iOS device would need 64bit support at this point.
While 64-bit was sold to PC buyers as primarily being for increased memory support, that's not the whole story, and isn't the driving force on mobile (32-bit ARM v7-A supports well over 4 GB of RAM anyway, via extensions, although each app's memory usage is limited to 4 GB).
AArch64 (ARM v8-A and above) is a significant break from 32-bit ARM v7-A (and below); it's effectively a new architecture, even moreso than going from IA-32 to AMD64 was.
The new architecture offers far better performance than the old architecture across the board, regardless of bitty-ness, and even outside of 64-bit INT/FP support.
I am an EE engineer. So if you are saying it improves those, you need to explain how.
It makes interoperability/compatibility worse because it is literaly removing compatibility.
My post was intended to be from the perspective of the consumer (and Apple), not from that of dead (or deadbeat) developers.
Backwards compatibility limits new iOS sharing/interoperability features and compatibility with new hardware features.
As you can see it also requires more dev resources due to required updates. And you could always make 64bit apps if you wanted to. So its only worse.
Backwards compatibility requires Apple's development resources to be squandered on legacy software instead of moving the platform forward.
What does security has to do with 64bit?
Supporting old code and an emulation layer opens up great potential for security vulnerabilities.
Performance - i rarely needed 64bit integers, so where is the gain?
Loading and running the emulation/backwards-compatibility layer adversely affects the system as a whole.