Should these sorts of widgets be the default implementation of those types of controls in desktop browsers? As long as they can be done with the same input information, this sort of input seems like a "user preference" issue.
Yeah, that's why you do it on the client-side. If the widget doesn't work on an iPad then an iPad browser shouldn't default those controls to that widget. A desktop browser could, though Nobody would be worse off, and nobody would be the wiser (except the user).
Looks like it would be very nice on a desktop though!