I've struggled through doxygen generated docs for C++ before, and I think one of the things that helps make javadoc more readable is due to the "stricter" (in a sense) structuring of the java language vs C++: namespaces & objects everywhere make grouping more likely to occur in consistent ways in the code base, which then gets translated to more readable auto-generated documentation.

This is something I think rustdoc (for rust) also has succeeded at, partially for similar reasons.