Why didn't the 1st-4th Hokage stay?

[super michael]

I never understood why 1st Hokage, 2nd Hokage, 3rd Hokage and 4th Hokage didn't stay. I mean it isn't like by them being in Edo Tensei they will cause any harm.

 

[Chikombo]

I never understood why 1st Hokage, 2nd Hokage, 3rd Hokage and 4th Hokage didn't stay. I mean it isn't like by them being in Edo Tensei they will cause any harm.

People need to die.

 

[minamoto]

People need to die.

exept tobidara..