I agree that the concept of namespaces is brilliant, but very difficult to read in practice. The rules around the different ways to specify namespaces also seem unnecessarily complicated - I always need to review the XML schema spec, and spend a bit of time on it.

I feel they should be as simple as (eg) Java packages; but the problem has different parameters in Java: there's less chance of collisions in Java, because you're just writing one module; whereas one XML document can merge different sources - it's as if arbitrary Java modules, written by unknown people, were combined into the one file.