You're trying really hard to have your cake and eat it, too. A key way that Apple has cultivated the it just works reputation is by doing exactly what they're doing here. They limit the variables. The OS is written for their own devices only. As new devices are rolled out, support for legacy devices is phased out. As a result, the number of hardware variables that must be anticipated by the OS is very defined and very limited. The same goes for software. The reason it just works is because Apple has never, ever tried to be all things to everyone.
Devices running iOS have only been in the wild for a decade. Despite the perennial belly-aching you read on this forum with every new update, the pace of innovation and improvement has been rapid. Even with that, the march toward 64-bit-only has been known and obvious for several years. Developers have had time to respond to it. The shift to a 64-bit-only framework is directly related to maintaining the it just works ethos. Apple is not going to hold back on that and sacrifice the leading edge to benefit poorly supported or unsupported apps on the trailing edge.
As for the the customer alerts, you think they're inelegant. Got it. You don't need to repeat yourself. Apple is going to drop support for legacy 32-bit apps, for the reasons stated above. They could either warn their customers or not warn them. I think it's much wiser to offer the heads-up. You don't. O.K., then.