Strictly speaking this doesn't make them a true 3d sensor, but rather a 2d sensor with an accompanying depth-map. In order for them to be true 3d sensors they'd be have to transmit information about both the near and far sides of an object simultaneously, for example.
Very true, a 4 dimensional being with 3 dimensional eyes would be able to look inside closed boxes, and see every side of every object at once. (just like we can see every part of a 2d scene all at once)
Not merely 2d + depth perspective.