As in previous negotiations, the DGA has decided that half a loaf is better than no loaf. Of course the reason the AMPTP offers the DGA half a loaf is in order to reduce payments (and power) to the WGA and SAG-AFTRA to 1/8 a loaf. If the DGA managed to think in the long term and unite with WGA / SAG, not only would they do better financially and creatively, but the quality of movies and TV would increase dramatically.
The old saying that "movies are a director's medium and TV is a writer's medium," suggests a reason for the DGA's lack of fortitude is apparent: the shift to streaming TV at Netflix, Amazon, Freevee, etc. signals a the commodification of direction. Among the British policiers that I watch, writers (Sally Wainright, "Happy Valley") and actors (Shaun Evans, "Endeavour") have begun to take over directing duties as well. No wonder that the half a loaf of stale white bread on the AMPTP's table is looking so good to the DGA.