Oh nice! I wrote something about my experiences with this very topic. (Link on bottom of this post.) My response can be basically that post.
Basically, I agree when discussing the author and the work, the gender can be used as a means of understanding the writer’s perspective, but the work should not be judged as a written work based on the gender. As for characters being ‘relatable,’ when it is flipped no one talks. There is a double standard in writing characters that are well, non white-men. Men get awarded points for writing women well, but when a woman writes a strong male character it is just glossed over.
I disagree with your thoughts on Harry Potter not being talked about in 50–100 years, because the cultural response has been very strong and has already lasted almost twenty years. Harry Potter has also expanded to other media. It will persist within its fanbase as they grow older and teach it to their children, and so on.