But that decision still doesn't really line up. Plants aren't part of the ground. The only plant matter contained in dirt is merely the decaying material in soil. I'm not sure how many people would consider plants "part of the planet" any more than the ocean or atmosphere. It just seems simpler to give Onua the Stone powerset along with Earth, and relegate Pohatu to, based on the polls, Lightning.
And if the move were simply to make Onua a Toa of Plantlife instead of Earth, I'd accept that. Pohatu could get all ground/rock powers then instead of Onua. My issue lies in combining two powersets that don't really have that much to do with each other. Earth entails earthquakes, eruptions of the ground, and as most people would say when not talking about Bionicle, throwing rocks. Plantlife entails creating living plants to strangle, block off, or emerge from under targets. Merging Earth and Plantlife is like merging Plantlife with Water or Air.