The list as a whole was strong on denotations, but weak on connotations. It doesn't answer the general question of why you would use "jejune" rather than "naive". Then again, it is very hard to capture these subtle word connotations by using more words. These words aren't just a great way to capture a particular idea and look sophisticated, they're also a great way to expose yourself as a poser not just by misusing a word entirely, but by using the word where the denotation holds but the connotation is off.