I know what you mean, I was surprised by the research they mentioned as well. But then I started thinking about the great teachers I know and realized that out of the top ten teachers I've known, only one of them has an advanced degree. It's positive intangible qualities that these teachers bring to the classroom that seems to make the greatest difference. These teachers educate themselves in best practices but aren't working towards an advanced degree. They do it because they are curious and interested in finding things that make a difference with students.... A graduate degree wouldn't necessarily help them towards this goal, depending on the program. These teachers devote a lot of energy to their students in their classrooms, and hoops and demands of graduate school can be a drain on this energy. I think that's really what the research is saying, as opposed to your thoughts of dumbing things down. I think it really depends on the teacher.