Yes, you might be right! Also, perhaps part of Rowling's success stems from the change in global markets, economy and digital media since Tolkien's time. Rowling, along with other newer writers, are able to tap into a literature market that is part of our now globalized and digitized economy which makes their works accessible no matter how niche of a work they may publish. Rowling's works, even when initially published, were able to be purchased and read by folks on opposite ends of the planet in a matter of seconds at best, or in a few weeks' time at worst. Also the tightly interwoven relationships between internet, film and literary media that we now take for granted, gives newer writers such as Rowling the advantage in getting seen and known easier over older writers such as Tolkien who had to wait for a ship to leave the docks or a plane to leave the airstrip for his books to travel...