The problem with NDLS back at the time of its introduction, (and even now) was that it has no place to park rakes. Which is why it has been receiving no originating trains (with the exception of Mahamana, NDLS MUV, CDG Shatabdi and a few more). Similar is the case of NZM. When introduced, YPR DRNT had to be parked idle for 3 days which neither NZM could afford nor NZM. So DEE. Also back then DRNTs had no halts. So it made sense.
Now it needs to be pared only for 12 hours and even if you keep the base as DEE, all it needs is a halt. Pretty doable no?