For a good design of XML files. This is indeed not a good design. As a bit of history, there was a fair amount of argument about what features went into XML1.0 itself.
People do use attributes in ways that have heterogeneous security requirements.
This is one of the contributing factors to the maxim that we can't expect people to design their schemas to our convenience. On the issue of application requirements, we've had folks argue this is, and is not a requirement. On the issue of complexity, we've had folks argue it's unnecessarily complex, and on this issue I tend to err on the side of simplicity unless it's demonstrated otherwise. I haven't made up my mind yet, as I'm still learning a lot in this discussion. Instead of being two complete proposals, something that could be easily plugged in.