Why are end stops NO instead of NC? (no replies)

I am using a sanguinololu 1.3a solution for my 3D printer. When I purchased my endstops they sent me NC instead of NO. Will it cause a problem if NC end stops are used? Why are end stops NO instead of NC?
I know that under configuration.h file
ENDSTOP_INVERT=false
Needs to be set.
What was the logic for NO end stops selection?

Thanks