Benefits

Safe to use
Egg powder and liquid egg are free from the risk of contaminated egg shells, as they are first pasteurized to eliminate Salmonella and other micro-organisms.

Easy Storage
They are packaged for convenience and minimal storage space.  For example, egg powder or liquid egg will require less storage space than their equivalent in a tray of 10 shell eggs.

 
Less Wastage
Shell eggs may break accidentally, resulting in mess and wastage.  Egg powder and liquid egg are free from this risk of breakage.