Many lolita dresses are made so that they ideally end at or just above the knee. Because she's taller, the dress would stop above her knee, and she probably thinks that others will think it doesn't look right or that it doesn't suit her body type, which would be apparent in photos as a well as on a runway. Of course this styling is a preference and subjective to everyone's own opinion, but I figured i'd explain this since it's a nuance for people who don't wear lolita, and was a bit much to add as a note.