You could just as easily say "When rpm can truly understand, say, maven goals and can be plugged into a java build system we'll be somewhere."
Just because java builds aren't done the same was as some linux distribution do them doesn't magically make it wrong.
The issue isn't the build system, it's that java libraries often don't provide the same API/ABI stability guarantees as a number of C libraries do. Exactly the same problem happens when C libraries don't provide those guarantees, such as ffmpeg, and there is a large amount of work dealing with that. The only difference is that not providing that guarantee is much more common in the java world.
There is also the issue of putting archives inside archives, but that is just how Java works and there are some good reasons it does work that way.