> If you want to be hired as a staff scientist, you need a PhD. If you have an MS you can't be a staff scientist. If you have a BS you can't be a staff scientist.

That's not entirely true, though as I understand it is becoming more true; there are definitely places that will promote to positions for which the normal route is a post-graduate degree based on a lesser degree plus experience (including publications under the rubric of experience).

Now, university faculty positions, degree standards tend to be ironclad, though.