Sexy > cute for the fundamental reason that idols are teenagers-to-young-adults, and sexualizing them, generally by choice, is not as problematic as infantilizing them, if at all. There's a difference between the semi-plausible Gee at an average age of 18, and that awkward backstage interview from last month where SNSD were forced to attempt aegyo when most of them are halfway to 30.
Of course, the idols should be comfortable, first and foremost. But there is a certain cut off for being cutesy, and furthermore a difference between "cutesy" and "anything that isn't dark/sexy".
