The main problem is duplication of effort, something these archives try, by definition, to reduce! But there doesn't seem to way a out of the dilemma: how do we create a repository of generic, truly reusable software modules that are language-agnostic? There is no inclination of the world converging to one single programming language, so picking one "universal" programming language is not an option.
Writing code for a VM isn't a solution, because in general
the real problem here is not solvable by technical means: it's fundamentally a social problem.
Groups of programmer's are uncomfortable using tools that are not written in their language of choice. This is for a combination of reasons ranging from mindless snobbery to intelligent conservation of effort.
This subject also comes up when discussing extension languages for programmer's development environments.
To quote what I've said before on the emacswiki,
"But embracing multiple languages necessarily involves sub-dividing the community. Even if there’s no actual fork in the elisp code-base, there would be splits in the emacs community – you need to be a perl programmer to further extend an extension written in perl, and conversely most perl-programmer’s will have little interest in assisting with work on extensions written in Java."