Lightweight, plastic construction allows for less manual labor in the field. Pipe stands can be stacked in the back of a truck bed versus hauling 4x4 cribbing wood. Plus, plastic does not deteriorate over time.
The cylindrical shape of the pipe stands allow for a stronger base than other options.
Pipe stands can be lifted from a truck and placed in it's appropriate position by one person. Repositioning of the pipe stands is made easier also.