Tunesmith, you might not find them sexy, but then those girls are competing in a dance competition not a beauty pageant. As such, they are being judged on their skill and creativity in that form of dance, and not on how sexy and feminine they are. Many of the dress codes that develop in sub-cultures are actually quite pragmatic. Street dance for example is essentially (as the name suggests) an outdoors activity done in the street and not a nice cosy dance studio (where dancers might be expected to wear leggings and leotards). You'll notice their clothes are multi-layered casual/sports wear (fairly standard principles for athletic exercise, ask any runner) and also loose enough to move about freely in. Their shoes are also sports shoes rather than high heels for example, which would make a lot of their moves impossible.