Why do people like Luna Lovegood?

I was just reading the HP series, and I realised that Luna Lovegood is a lot of peoples' favorite character. I love her too, how she's so different from everyone and so interesting & quirky, but I feel that she's less complex and ..like not as important? I know she fought against the death eaters, but so did many other of Harry's friends. So why does Luna seem to be a significant character in the series, and why does her name get to be named for one of Harry & Ginny's daughter's middle name? I felt like it should have been after someone important; like tonks or even his best friend, Hermione. Please don't get me wrong! I still adore Luna but just don't think of her as a fav.character. And if she's your fav. character, why??