There's definitely a problem with trying to sound smart just by using complicated words, because often that person just ends up sounding like a jackass. Case in point: a journal article written by the same person who wrote my current math texbook. The journal article was published shortly after that person earned their Doctorate, and they wanted to sound like a Dr., I guess, because the article--which was on something extremely simple--was so damned hard to understand. And it didn't have to be.
There's nothing wrong with being simple, but there are so many beautiful words out there with slightly different connotations or just better "feels" than their synonyms for an occasion. Why not try and learn and use them appropriately, for fun if for nothing else? As long as the connotation of the word is correct, I don't have an issue. If I don't know what a word means, I ask, and others should too.