We've all seen how much Madara admires the 1st hokage but as I've been reading theories about who created Zetsu (or Tobi for that matter) I've started to think that maybe the 1st really did admire Madara.
The 1st had no competition. If edo Madara is any indication then Hashirama must have been almost bored before Madara came along. I imagine him pleading with Madara to combine their strength for the good of the ninja world.
Maybe Tobi is a joint creation of Hashirama and his brother Tobirama (something about his name and his edo techs just begs the connection) to try and salvage Madara's power. Unfortunately that power is an empty mass of hatred and despair that just wants to collapse the whole world on itself like a black hole. Tobi could be the result of good intentions gone wrong.