If they want to imagine the world for themselves, they can write their own novel, can't they?
When you don't read about very many characters who look like you, sometimes it's nice when an author acknowledges when one of them does, even if it's not important to the plot.
I can see your point... I like when I get my hands on a book that features a strong female protag. But as a writer, I have a story to tell. I try to describe everything crucial to the plot and then let the reader built the world in her mind. That's because, as a reader, it's my personal preference that the author not use too much description- it slows down the book for me. I like to read and use my imagination... if I didn't want to use it so much, I'd just watch tv and movies (which I also enjoy, of course.)