You're missing the general idea that silver is overused, even if two Toa don't have any. But I don't really mind, I mean, protodermis is silver, and that's what they're made of, apparently.Still though, it's really only on the weapons. They would be silver since they don't have any life energy, which I suppose is what gives armor its colour. And let's face it, when was the last time any of us saw a green axe?
Most of the sets that have silver on their bodies, though - Nuva and Hordika, mainly - all suck. The Inika toned it down a bit, reducing it to the weapons and such. Kongu and Matoro had silver on their bodies, but they're kinda crap. X-D Nuparu, not sure if those claws are his hands or whatever, but they look okay to me, just would have been better in black.
With the Mahri, the ones with more silver are the ones that suck more. Jaller has basically no silver, only his sword and pipes, and the crab has silver legs. Nuparu is crappy, and has more silver, coincidence? :-P
With the Nuva, I think they will have silver, but otherwise they're pretty much doomed to look completely different from the originals, which is good and bad.
Anyway, I think they should tone it down with the silver, basically. A Jaller Mahri-like scheme would be acceptable for your standard Toa sets, which the Nuva are not, in the end.