Hmm. I always liked a gap between legs. I used to do a lot of fashion designs in past so I was always drawing real humans according to fashion models anatomy, very slim, very high. Those hips are stylized though, people don't have so curvy shapes. I thought it looks nice though, that's only stylisation. However their feet in the picture wouldn't touch each other, so even I, when standing that way, have a gap between legs, but it's size depends on year season. In winter it dissapears (no sport, a lot of food, sitting and drawing), spring - it starts to appear (more sport, less food), summer - there should be a gap (a lot of sport, hot weather, less drawing).
Gap's size also depends on pelvis width, some girls are having short pelvis, as males will have always legs together. I like it wide, I think it is very feminine, and the crotch looks like a pillow