1) It's quite common to study for PhD while getting paid for it instead of paying for it - and in that case, it should be treted as a fun and enriching (though not very high paying) job for a couple of years instead of "delaying 4 years". Getting into a huge debt for it is a whole different thing, though.
2) It feels that this problem is partly USA-specific. Sure, other places may have noticed similar tendencies but not as sharply; and science is very, very global - I'm seeing a lot of great researchers moving between countries/universities every 5-6 years based on where the major research projects in their area are happening & funded.
In general, a solution would be to try to decouple research from teaching instead of mixing them all under PhD/professor positions - the future tendency seems to be with much less people needed in teaching (due to changes in society, student funding/loan systems, MOOC's, etc) and thus more PhD's shifting towards research.