It's not supposed to be. It's supposed to illustrate a trend. These are among the most popular fantasy works of the past century. I challenge you to compile a list of counterexamples with such high profile -- human-elf-dwarf-hobbit stories that aren't either openly derivative of Tolkien and D&D or explicitly set in a D&D world. And even if you can produce such a list, it still doesn't contradict my point. The idea that an assortment of nonhuman humanoids is a necessary or desirable element to fantasy is simply false; the existence of these books at the top of fantasy bestseller lists proves that, no matter how many other books there are. In short: human-only worlds aren't only possible, they're normal. And yet I'm seeing a bewildering amount of negativity towards the concept in this thread. Does everyone saying humans are boring here also say that A Wizard of Earthsea or A Game of Thrones is boring?