There's a problem in that a lot of hacks and patches are applied to people's libraries, some libraries are replaced completely by third parties to alter functionality in some way, and that would be difficult to govern properly.
Of course the user could just say no to updating these libraries, but that requires them to remember which libraries have been patched or replaced, which old versions they might need for compatibility... it all works against the convenience you're trying to foster and you get GNU/Linux Syndrome, where any attempt to simplify an aspect of the computer's operation ends up complicating things further.
