Basically here's what I tell people who are longing for "darker" Phish or more outside the box playing:

You have a lot of older Phish you can listen to that hits those places. In much the same way you don't find current Phish stepping outside of the established musical paradigms of "agreement", you often don't find anywhere near as much agreement, respect and frankly "good taste" in older jamming styles. The music Phish plays now makes sense for them, and who are we to argue with them really?

In addition there, is plenty of music both old and new that also will take you to those zones: krautrock, free jazz, noise. While it is certainly convenient to get EVERYTHING from one band, Phish doesn't need to be everything at all times. Expand your horizons and never stop searching for the sound.