Thank you Ghid!
Oh, I noticed a thing by your reply!
I think the reason Toa Mata(especially Tahu) didn’t have a lot of armor, it may for they has to have a payloads and slots for the ability to wear the Golden Armor! 
(or maybe they already wearing a thin-armor at that appearance, but it doesn’t seem to me.)
I think the canon Helryx’s design is perfect as first Toa, of course including " The unsophisticated mechanics to function".
I can imagine now why Krakua has unique form:he looks like Helryx in partically.
about Inika, I have a hypothesis.
they has transformed by Red Star’s energy, but remember a thing.
Red Star is a one of functions of Great Spirit Robot. this mean no-one can’t effect its system. (May Teridax technically can, but he never did.)
Then, I guess The Star have a designing data of “Ancient Humanoid being”…yeah, I want to say, this is Glatorian.
So my hypthesis explain why Inika is similar to Glatorians.
their design has no effect by many generations of “memories of Toa’s appearance”, and have a reason why their mask is “Organic”.
(Of course, “the circumstances for selling toys” are different. 
)
and about Jovan…Oh, I feel it’s truly “not my business”, right? 