People who use long and fancy synonyms for simple words often do so solely as an attempt to obfuscate their message and seem smarter than they actually are, but in doing so they are making their message less clear, and that's not an effective form of communication. People who do this think they're the only ones who do this, but I've seen it time and time again from English majors. Awkwardly shoehorning GRE vocab into your writing looks bad and it doesn't fool anyone.