Also, Lovecraft had good relationships with other authors and collaborated with them, and effectively made the Cthulhu mythos open source before that was cool. Rowling on the other hand...
"On the other hand Lovecraft stories work because he was racist. Fear of the unknown etc."
Well when you get right down to it, the wizarding world of harry potter only really functions because of the author's hardcore belief in the importance of the status quo and the existence of groups of people who are inherently evil... Not saying the premise wouldn't have worked without that but it would have been a really different story