> Ideally, a newer interface would provide scan codes instead of the escape sequences. Not having to deal with ‘escape’ like we do today would simplify things.
While I agree the Unix tty model is crufty and old, this particular feature doesn't require any changes to it. The later models of the real DEC terminals introduced a mode called DECPCTERM to send PC compatible keyboard scan codes, with escape sequences to enable/disable it. Terminal emulators very rarely implement it, but there is no reason why they couldn't. And there is no change the Unix tty subsystem design required to support it.
While I agree the Unix tty model is crufty and old, this particular feature doesn't require any changes to it. The later models of the real DEC terminals introduced a mode called DECPCTERM to send PC compatible keyboard scan codes, with escape sequences to enable/disable it. Terminal emulators very rarely implement it, but there is no reason why they couldn't. And there is no change the Unix tty subsystem design required to support it.