Thats is rarely the case with any material.
Materials that we are talking about he will show there brittleness or resistances to breaking with deformation to be more accurate with their thickness.
Glass, ice, sapphire, etc etc become more prone to shattering the thinner they get, less impact required. Its not until the actual material is altered that it can be made less brittle, tempering, adding material like in safety glass etc etc.
The entire selling point of Gorilla Glass 3 is with a different formula/process they are able to make thinner then GG2 and be just as strong. Obviously if all they have to do was just make it thinner they would have done that with GG1.