Then you need to re-imagine the system in such a way that junior scientific programmers (i.e. Grad Students) can at least imagine having enough job security for

Then you need to re-imagine the system in such a way that junior scientific programmers (i.e. Grad Students) can at least imagine having enough job security for code maintainability to matter, and for PIs to invest in their students' knowledge with a horizon longer than a couple person-years.