It's one thing to replace default gnome applications with others put to leave the gnome application as optional. Like when firefox replaced epiphany. Does such a switch really impact application developers who are writing to the specifications set down by the gnome project? No.
It's quite another to tell developers point blank that a framework component like the notification area won't be included at all for users to optionally put back on their gnome panel even its its not there by default and they they must adapt to the unilateral decision making of Canonical regardless of what the GNOME project has defined as its development framework.