Java treats each package as independent. For example, package local don't extend to any "sub" packages. I suspect using the hierarchy in a meaningful way would be valuable but Java's design was to make everything as simple as possible.
Or is there any reason (other than they just didn't do, not that they couldn't do it)?
The problem is backward compatibility which might break older programs. I suspect this is solvable.
In truth, most IDEs manage your imports for you and I don't even look at my imports any more. Certainly avoiding import * is preferable so that all classes are explicitly imported.
