It was created because eGO at the time was expanding fast with so many members, they (Council) needed people inbetween (House leaders) to help manage them. Also it was created to help create friendly competition and bonding... smaller groups, better to get to know each other. However competition turned into rivalry and feuds... so they decided to not create it in other divisions.
As of now you would join TF2, CS, or Call of duty and you would have no idea who these other Admins are unless you play with them regularly. The advantage of houses were, you would know who were in your group even if you didn't see them in-game.
But eGO is so big, I can't even keep up with my own house (The Raiders). I'm too busy playing TF2, or Insurgency to pay attention to the "application" forums... sadly.