Mask powers discussion

In mnog the toa are seen to use not only their 6 great masks but also the powers of the turagas masks (noble or great im not sure) so its safe to say they each had to find 12 masks each not 6, ( unless they were noble masks and they were more of a side quest compared to the 6 great) why did the toa metru not have this mask swapping thing, i would have liked to seen abit of that. I know the toa mata are special but it was all very convenient that the 6 masks they were destined to find opened the lair to makuta. Theorys only no marketing rationalising :)