2D is reliant on the infra-red beams being broken in a straight line with the doors, but 3D has a bigger detection zone which covers the front of the doors, and therefore will trigger the door detection earlier.
As a result, by upgrading from 2D to 3D detection it has been proven to reduce door accidents by up to 90%, please see Copenhagen Airport case study. 3D detection is very widely used in Hospitals & Airports, as well as Council buildings and Housing Associations, as these generally have higher door damage rates.