As a writer, I'd just like to say that it is freakin really really hard to work with science and magic. To an average reader, the scene with Jasnah makes pretty good sense.
Nothing will ever be perfect, unfortunately (Except for a spiritual ideal of something!) and so if Brandon went in depth on how soul casting works with blood, then many readers would be left confused.
However, you do make very good points in this article. If I ever write a magic system with blood I will try to do my research!