I don't see many "I quit!" or "don't go!" essays from science, but you do see scientists expressing concerns about continuing to accept so many PhD students who won't have a clear career path.

This seems especially true in biotech, though part of their concerns seem to be about how the new students will compete with them for grant dollars... see http://scientopia.org/blogs/drugmonkey/2013/01/28/shut-off-t... for an example.