BSE has said to me that they tried to balance precision cutouts with having an allowance for application so the majority of people can put their skin on easily and error free. I can attest that is definitely the case. If you lineup the camera/flash cutouts up top and the lightning port on the bottom the rest falls into place and fits well. I had no trouble with their corners either. For friends that want a good looking skin and haven't put one on before I recommend BSE for that reason.
That's PR speak for: we didn't want to bother with precise cutouts.