Essayists of our time

I've been taking an essay and article writing class this semester and one of our required textbooks is called "Essayists of our Time". It is a collection of works by famous essays writers of the the 20th century. All of the greats are there, Twain, Orwell, Dillard, Thoreau. What do they all have in common? They are all pretty much the same. The same artistic style and demeanor. There are few ideas really represented in their works, Thoreau is the only one that really seems to have represented sincere originality in creating ideas. His ideas created a movement that has evolved over decades! This being said though I am not saying they were not great writers, I would be lying if I made such a claim. They are role models for those of us who are developing writers.