This isn't a new or unique move; Apple has never prioritized backwards compatibility.
If you're a Mac user, you expect this sort of thing. If running neglected software is critical to you, you run Windows or you keep your old Macs around.
It's a bizarre assumption that this is about "neglected software."
A lot of software is for x64 only.
If Rosetta2 goes away, Parallels support for x64 binaries in VMs likely goes away too. Parallels is not neglected software. The x64 software you'd want to run on Parallels are not neglected software.
This is a short-sighted move. It's also completely unprecedented; Apple has dropped support for previous architectures and runtimes before, but never when the architecture or runtime was the de facto standard.
Nevertheless, running x64 software including Docker containers on aarch64 VMs does use Rosetta. There's still a significant valid use case that has nothing to do with neglected software.
I seem to remember 68k software working (on PowerPC Macs) until Classic was killed off in Leopard? I'm likely misremembering the length of time, but it seems like that was the longest backwards-compatibility streak Apple had.
If you're a Mac user, you expect this sort of thing. If running neglected software is critical to you, you run Windows or you keep your old Macs around.