your system, as originally described, seems to have less of this kind of redundancy than the current system

I see what you're getting at. It'd be fairly easy to build in whatever kind of redundancy you like, including the current level of redundancy, by having multiple widgets. In fact, you can strike any balance between convenience and security that you like — multiple backups of the same omnibus widget (with the keys locked to the widget I'm using, so that widget can be revoked if stolen), multiple widgets with different stuff on 'em, whatever. A lot depends on the cost of manufacturing the widgets.