There are reasons a person might be unclear. For example: Subtlety might be in order to be sensitive to eavesdroppers. A person might be vague in an effort to hide a secret. Though, the secret might be that the person does not know what he is talking about. His lack of clarity actually might be obfuscation. Or maybe there is no secret at all. Maybe the person just cannot string together coherent sentences. There are many reasons for being unclear.
Another one of those reasons is this: A person might know exactly what he is talking about and how to say it clearly, but clarity would open him up to judgment. It is hard to judge what is not clear. It might be good. It might not. Who would know? After all, it is not clear.
The propensity to be unclear for fear of negative judgment is accentuated by a natural human reaction to confusion. The receiver of unclear communication regularly blames himself but keeps quiet about it for fear of being perceived as ignorant.
“Is that guy chewing on marbles or am I an ignoramus? Surely the reason I don’t understand him must be that I’m stupid.” That is a common reaction when listening to someone who sounds confusing.
Thus, being unclear is doubly rewarded. Not only does it avoid negative judgment, but it regularly elicits hushed insecurity. Being unclear is a safe way to communicate.
But lack of clarity will never inspire people. Better to speak clearly and risk the possibility of negative judgment. Be transparent and give people something to react to.