I believe my daughter's dance recital costume, by the way, is a sequined leotard. I think there is a very short stick-out-horizontal type skirt and butterfly wings that attach to the wrists for her ballet number. Then they take off the skirt and wings for the tap number.
She's four, and this is the south, and in May she is usually found in a swimsuit or gymnastics leotard. June, July and August she barely gets out of a swimsuit.
But I get that the costume under discussion is sorta weird and you could feel like there is something missing, so I fully support her in adding bottom coverage.