The trees have taken goo all around them. You find thrall feeding around one. The trees appear in the center of taken blights. The “voice” sounds like the one your hear when you first enter the Last Wish raid. The voice says “you might have been queens and kings of the deep, but you have not replaced me?” Sounds like Riven imo. “The traveler waited a year, why wake now?” Asked ghost. What if it’s not the traveler, but some sick form of taken, corrupted light wielded by Savathun or something?
If our new ability trees are secretly from Savathun that would explain why they're so half-assed and don't seem to work so well lol
The trees represent the light and the goo is the taken infection on the planet, the taken can sense the light so the gather to feed on it. The traveler doesn't have a human voice so it just uses a collection of voices to communicate. The quote is from tolland after guardians kill oryx in the taken king raid, the traveler is just acknowledging that you didn't fall to the lust for power and take the throne. As Ikora said, "When we grow in power so to does the Traveler." I think it just didn't have a good reason to speak or it just toke us a while to figure out it was actually talking.