I've never noticed that before. I just tried it and you're right, same thing happens to me. The material looks find in renders and the swatches look fine in Hypershade. But in the texture editor, it's black and in the view port it's black. Even if I use undo feature, it still stays black. If I assign the shader to another object, it's black on that object too. That's pretty annoying for sure.
Don't be satisfied with what you can do but rather strive to do the things you can't do!