First theory: Animators didn`t put much effort at designing them.

Second theory: It`s a "subliminal" message in favor the LGBT community, to make us see a different kind of family (you know, love and tolerance)

Third Theory: Breezies are hermaphrodite and reproduce like worms

Fourth Theory: It`s just a kids show after all and the gender of these things doesn`t matter, specially when they look cute.

Kinda hard to tell what gender these things are huh?