You're missing the import of the Profzi Scheme (http://www.phdcomics.com/comics/archive.php?comicid=1144): the lower levels of the pyramid are necessary. Graduate students and post-docs aren't really independent researchers pursuing their own ideas, and basically never have been. They're (highly educated, scientific) laborers who work for a boss.
By most metrics, a system in which most of the actual work is done by low-paid laborers with long hours - who are then thrown out as soon as they've got experience and tribal knowledge! - is not only an abusive system but a stupid and counterproductive system.
By most metrics, a system in which most of the actual work is done by low-paid laborers with long hours - who are then thrown out as soon as they've got experience and tribal knowledge! - is not only an abusive system but a stupid and counterproductive system.