The best way to make this case is simply to ask what evidence exists to say that we are no longer able to communicate as well as we once could. It is very difficult to prove that we are communicating less effectively than we previously did.
First, we have to ask if people are less effective at getting their messages across to other people today. It is very difficult to produce empirical evidence to test this theory. Therefore, we cannot conclude that we are less effective at communicating messages.
Second, we must consider the sheer volume of communication that we engage in today. Only a couple of decades ago, there was no email, few faxes, and no cell phones. Long distance calls were fairly expensive. Today, there are many more ways in which to communicate. This means we actually spend more time communicating than we previously did. We have more ways to communicate, meaning that we have more of an ability to communicate.
For these reasons, it is very difficult to argue that we are losing our ability to communicate.