If anything comes from this post, it's that it's a talking point I wonder for what D4 could do to do this better. Especially with a character as nuanced as Lilith. I'm no game designer, but I'm curious what others might think is a good way to capture the spirit of our beloved demons, tell a good story, keep us moving along nicely objective to objective, and what ideas there are to make this achievable in an ARPG genre. That being said...
Azmodan's demonic phone calls where he frequently appears to tell me his evil plan and how I will never defeat him make him seem.. like a joke.
Diablo portrait dialogue is arguably more guilty of this: "You may have beat the previous step in my evil plan that I said you wouldn't, but it matters little, NEPHALEEEM! For you cannot stop my Hell Rifts!" wink wink
Me: "Oh, uhh.. I guess I better go do that next. Thanks Diablo!"
I understand their arrogance in these moments, thinking they get this win in the bag. But this method of story telling (more like holding my hand telling me where to go) is even ridiculous on lesser characters like Magda: "It matters not that you found the last piece of the sword, I'm already killing the most beloved protagonist of the franchise in his cabin as we speak!" evil cackle
Diablo spoke one phrase in D2 and the phrase still quakes in my bones to this day: "Not even death can save you from me."
I'll find my way through the game, so I say, don't force screentime on Lilith or other cherished Demons of the franchise just to point me to my next objective. Make sure the time they have when we interact with them is powerful, meaningful, and arguably most important, true to what they represent as characters in the franchise.
Tl;dr I'm no game designer, but I wonder how antagonists could be better represented in the story and furthering the plot, without using evil walkie talkies in an isometric ARPG.