Edison is notably overrated. While he does deserve some credit, his approach to R&D was infamously brute-force. Tesla noted, “If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.” He also infamously took credit for the inventions of his employees--the long and impressive list of things Edison invented is really a long and impressive list of things invented at Edison's lab.
While it's hard to argue with success, not every successful man should be a figure of unquestioned admiration. Edison was famous in his day, and remains famous today, because he had the best PR and marketing in the business.