You know, ever since Lewa got his rather unnecessary change to a Toa of "Jungle" in G2, I've been asking myself why him and not the Toa whose element legitimately doesn't add anything: Pohatu.
Now, I know the whole "Stone vs. Earth" debate goes waaaaaaaaayyyy back, but I still feel like it's never really been resolved. Just how is Stone different from Earth? And the reason I ask this is the fact that the surface of a solid planet tends to be made of rock. This is the case for all the inner planets in our solar system, and we've no reason to believe this is different anywhere else; and, in both generations of Bionicle, the terrain is clearly made of rock, just like it is here. But if Toa of Earth control the Earth, and the Earth is made of rock, how do they differ from a Toa of Stone? This isn't like Ice vs. Water, wherein the relevant Toa control the same substance in different states of matter which have different properties, because Toa of Stone and Earth would seem to control the exact same thing, just in different ways.
It makes sense, therefore, to have Pohatu made into a Toa of something else. In my mind, Iron seems like the most logical choice, but maybe you have better ideas than me. So, I present you with the titular question of this thread: Should Pohatu get an element change in any future generations of Bionicle?