Well, it does work meaning it'll sit there and show that there are no messages. But if libmessaging-menu0 is installed, but no applications use it, it'll sit there and show there are no messages. So depending on libmessaging-menu0 is pointless as the real issue is that it needs applications using it. Those applications should depend on libmessaging-menu0 if they so desire. They could use DBus directly if they wanted.
Well, it does work meaning it'll sit there and show that there are no messages. But if libmessaging-menu0 is installed, but no applications use it, it'll sit there and show there are no messages. So depending on libmessaging-menu0 is pointless as the real issue is that it needs applications using it. Those applications should depend on libmessaging-menu0 if they so desire. They could use DBus directly if they wanted.