I think K-pop has already firmly established that for the vast majority of new groups debuting, a good song alone isn't going to get them anywhere. If female idols are comfortable with ditching layers of clothing, then they have my support.
For the currently popular girl groups, no one gave a damn till after they transitioned to sexy concepts. Was anyone even talking about Stellar a year ago? What was Girl's Day's situation before shedding some clothes and dancing more provocatively? Where's AOA's band unit?
If they want to make an impact, then by all means, make an impact. I'm going to say the odds of a new group having a long running career amongst so much competition is pretty low, so let them do what they can to grab their fame for however long that will last. If that involves being bluntly sexual to a society that's afraid of their genitals, then more power to them, as long as they're comfortable.
5 Gifs down below. Click on the Gfycat/Gif links for the larger sized versions.