I totally agree with you. There is a big age gap between protagonists I read about. Usually the YA books I read feature someone aged 16-17 and then the other books I read are mostly about adults aged 30+. Not that it's hard for me to empathize or connect with the main characters but being 20 myself I'd like to have some stories feature someone around my age. When I write I don't think I can make main characters younger than 16 because I honestly can't remember what it was like before then and don't have the experience beyond 20. Before reading this post I hadn't heard about New Adult. . .but I would definitely jump on that band wagon.