Different swimsuits

The new suits take about a half an hour to put on, and are not particularly comfortable - have you noticed how they pull at them....

The full suits give their real benefit in strokes like freestyle.  So when they can they go to pants only, short legs.... 

Piggybacking on sesh ... yes, the full body suit is so tight that it is counterproductive for events like butterfly which requires a different kind of shoulder rotation than freestyle.

But I read this at swimmingworldmagazine.com and it presents a different kind of perspective:

The result is an engineered swimsuit whose 3D anatomical shape has a Core Stabiliser with a corset-like grip to support and hold the swimmer so they can maintain the best body position in the water for longer without losing freedom or flexibility of movement.

For those of us who swim butterfly, you'll understand how your body/torso moves much differently during butterfly than during freestyle. With butterfly, your abdomen drive your  hips down as your chest/upper body drives upwards (and your arms move out of the water). With freestyle, you don't have this kind of up/down vector propulsion - in fact, you want your torso to be aligned horizontally but rotating side to side. So, if the point of the suit is to keep your torso in a "corset-like grip to support and hold the swimmer" then this would be ineffective and, perhaps, counterproductive with a strok like butterfly. 

That's my guess based upon that quote.