I would personally like to see Nightmare Mode FPs where two things take place:
CROWD CONTROL makes a return. This forces groups to socialize to some extent. It also gives room for error, and a need for coordination. "Trash skipping" dies I think trash skipping is absolutely ridiculous, and the reason why groups just BLAZE through FPs, and really trivializing the content.
I absolutely love trash pulls like the first pull in Red Reaper, the 5 droid pull in Athiss, the 4-boss fight in Mandalorian Raiders or HELL... heroic missions! I have often found my group dead or hanging on by a string at all of these - despite group experience. Oh hey look at that... I mentioned all the FPs that aren't HM yet too! So that was a great suggestion as well.
There is more satisfaction and less bore to me when there is social interaction, but more importantly, topped with a REAL level of difficulty.
TL/DR: Trash skipping, lack of crowd control dynamics, and no incentive to communicate leaves for a shallow experience.