We play a variant without the robber where a 7 means you just draw a resource of your choice. Much preferred if you aren't looking for a competitively enhanced game. :-)
We have a house rule that we re-roll 7s in the first two rounds. This after a 6 player game where the first round saw most people rolling a 7. It didn't particularly screw anyone, but it's just not a fun way to start the game.
Even with that rule, we usually only use the robber to hurt the leader. During the early game when nobody is clearly ahead, we prefer to place it on poor production fields, and use it just to steal a card.
This is not just fuzzy feel-good pacifism, it's good sense, because an enemy is not an asset, and it's harmful to make yourself a target. Hurt people who deserve it, but otherwise just go for the card.
Actually hurting someone with the robber at the beginning doesn't make sense even economically - most of the time you need to be able to trade with them.
My father once caused a game-long shortage of bricks and nobody - including him - was able to do anything. Lol. :-)
