I agree with this sentiment. Greg even say’s that even when Nidhiki lived there Matoran weren’t open to Toa’s help:
“11) Why does Nidhiki say that on his home, " Toa struck from the shadows or they didn’t live very long”?
11) Because it was a dangerous place for Toa to be. Not every land is welcoming to heroes, the same way not every place in our world is happy to see police."
Also Matoran could go their entire lives without seeing a Toa, even on Metru Nui:
“Some Matoran, even on Metru Nui, had never met a Toa before. For example, the transport manager that Matau once met in Le-Metru had seen Toa a long time before but had never met one in person. Still, he had heard legends that Toa were meant to protect the Matoran and keep them safe, which encouraged him to trust Matau.”
I believe Nidhiki would share similar armour to Krakua, but mostly Metru styled. This is because Lariska mistakens Nidhiki for a Metru Toa:
“I guess they don’t teach dodging in Toa training,” the female Dark Hunter said. “No wonder your city is falling.”
We also know that Nidhiki’s chest didn’t mutate as the Shadowed One explicitly didn’t mention it:
“Nidhiki’s head and arms had changed their shape. Most grotesque of all, his lower body now resembled that of a huge, four-legged insect.”
As for Krakua, if a Matoran could transform into a psudo-Skadi from thinking they were a Toa, I would be surprised if a drawing of a Toa couldn’t be used as a basis.