Note how most of the looks posted are the longer hemline - it's designers keeping the length sexy.
It looks great.
If we're talking about slits, I hope you'll excuse me mentioning slits up the
back of clothes also, starting with Balenciaga and Bouchra Jarrar couture for winter, and then to Proenza Schouler and Isaac Mizhari (
majorly) for spring.
Screencapped by me from the Balenciaga A/W 10-11, Bouchra Jararr Couture A/W 10-11, Proenza Schouler S/S 11 and Isaac Mizrahi S/S 11 shows