like you,I dislike the fact that both Onepu and Macku didn't become Toa
The only explaination I ever found was that they wanted 6 Matoran with the 6 great Kanohi olda masks
And the Onepu VS Nuparu was because they wanted an inventor in their team,too bad,I really would've liked to see a purple Toa.
And Nuparu really needed orange.