From a design (e.g. party comp) and community standpoint (overall willingness to take on challenging DF content) it's just not practical.

NM was a good opportunity to make something accessible yet still somewhat challenging as a way to draw people into raiding. With i190 rewards, something closer to Ravana in difficulty would make sense. However, history has shown SE enough times what would happen (Thornmarch, Steps, The Vault, etc.) so they knew to just make it faceroll easy instead to avoid the inevitable outcries for a nerf. With that kind of scenario to consider, the reasoning of "I don't want to use PF" is hardly going to persuade SE that Savage in DF is a good idea.

As for Extremes, I'd be indifferent to those being in DF straight away, considering they've done it before.