I personally think they are really cool and made this whole drop quite a bit more interesting! They introduce new decorative elements for animated builds like fountains and steampunk pipes and stuff, and they can be used in entity transport of all kinds.
My only disappointment with them so far is that they’re so random to trigger, I wish we had a way to trigger them manually somehow. Perhaps the first time they’re formed, they could immediately spit out a geyser? That would make them piston-activatable.
They’re kinda great. In fact, the whole drop is great. And I agree that having them be triggerable would open more possibilities. Hopefully they hear feedback about that and take it to heart.