I’m a bit reluctant to use namespaces because lots of people will have written code that just has “juce::” everywhere, which would need changing. I’m also keen to keep the namespaces short. But I understand your point, and was thinking about it - maybe it’s something I’ll change in the future.
But as far as doxygen goes, using namespaces actually wouldn’t be any easier than adding @addtogroup, because annoyingly, doxygen doesn’t actually parse all the code properly, it just reads each .h file separately, so unless every .h file contains a namespace declaration, it won’t know about it. And the way all my code is structured, none of my headers contain any namespace info, except for the top-level ones. So for this to be visible to doxygen, I’d need to add a (doxygen-specific) namespace to all those hundreds of files.