I have to weigh in on the "horribly wrong" side. The girls had some good dance moves, but also made a lot of mistakes, and there was too much shaking and hip-thrusting going on to see their talent.
I'm no prude, and I have a dd in competitive dance, too, but I have never seen such a skanky-looking costume in a competition, even on older girls. There were a couple that came close at our last national competition in Las Vegas, but those were 15-18yo's, their routines were far more tasteful and
many parents in the audience were saying some of the dancers looked like they belonged working on the strip.
Like others have said, to me it's the whole package that is gross. The costume alone might not be so bad if they were doing a tasteful jazz routine. The chest/hip thrusts are common in hip hop, but hip hop costumes usually include baggy pants or long shorts. When you put it all together, the Frederick's of Hollywood look, the pelvic thrusts with spread legs wearing short shorts, the shakes and shimmys, the pursed lips, licking fingers, ugh. Disgusting. I don't even want to watch an adult do that, let alone a child!
The outfit might cover more than a bikini, but swimming and building sand castles don't involve pelvic thrusts on a stage, so they are not comparable. Different clothing is appropriate for different activities and swimming/tanning requires the least. I would hate to see the standard of propriety of all clothing be based on the bikini.
Like someone else said, I am so thankful that our studio uses age-appropriate costuming and choreography. Our dancers do very well at competitions, too, so I know that you don't need to imitiate a skank to impress a judge.