A significant part of language may be learned intuitively, but only through the study of grammar can we learn to master the art of articulation. Anyone who wants to communicate as effectively and influentially as possible will benefit the most from studying sentence structure and how to formulate concise but powerful statements.
Simply knowing what "sounds right" versus what "sounds wrong" is not enough. One needs to understand why something sounds right or wrong in order to internalize the standards in speech patterns and use them effectively.
Miscommunication happens all of the time, and this is mostly due to poor speech patterns being exercised. This can be minimized, if not eliminated, by explicitly understanding the rules of grammar.