Semantics, and outdated at that. "Apps" on a smartphone or PC today includes a wide range of things. Increasingly you'll find the distinction blurring.
Current x86-32 emulation is already quite decent. x86-64 emulation is nothing but a boon to users, and will vastly increase compatibility with the field of x86 software. Granted, native ARM binaries are far better, but it's great to still have reasonable x86 capability.
It's also not pure emulation, every bit of MS code these programs rely on (Win32 libraries, for example) are already compiled to ARM which helps.