The Lego minifig version is basically a pink minifig head with a softer plastic body formed around it. It has nice snake-like tentacles and a leering, evil demeanour. The Kinder version has grippers on its shorter arms, to hold weapons and accessories from the figure range and a seriously peed off expression.
What I like about the figures is their simlarity to the Kelloggs Crater Critters from 1970, especially the tripedal King Crater, who does look much more benign, if not completely spaced!
But a possibly more interesting reference point is Kraang's resemblance to Terence Cuneo's beautiful painted illustrations for Well's 'War of the Worlds' which appeared in 'Tell Me Why' Magazine in a brief serialisation in 1970. Cuneo took the text literally and produced a wonderfully glaring, inimical Martian, 'glistening like wet leather', perched on the edge of a pit. The paintings stuck with me as a boy and unsettled me slightly with their realism. The Martians and the industrial looking tripods are for me, the definitive take on Wells creation.