As far as I’m concerned they’re explorers, not super-heroes. Thus the backpacks and practical clothes. I gave them their own colors as a sort of tribute to the Thunderbirds, Bionic Six, Super Sentai, Galaxy Trio… basically all the teams the FF inspired in the first place. But hey, credit where it’s due: I first saw the color thing done here.
Also, Ben’s skin is basically clay, rather than a pile of pebbles.
Oh! Lookit this!