But, as you know, Even if you read a notification, it still there till you click on mark all read, so if you add and option to otomatically prune notifications which already read on notification bar,
I hope you understand
I am sorry but I really think it doesn't make sense to mark them as read. You should be responsible to click on it if you want to view it. It serves as a reminder We could add this in the future as a settings perhaps but not now.