For most of human history, it was the exact opposite. What was brief was least important, as usually the format of a statement dictated the attention it deserved. Shortness was equated with incompleteness, which meant that things communicated quickly were more suspect and were considered less trustworthy (a rapid-fire sales pitch or the unknown threat of someone "of few words" being two examples). The common bias was that brevity could be the same as stupidity. It wasn't consistently the case, of course, but it was believed that someone saying little often meant that they had little worth saying.