They lowered the cut for people who didn't need it. Massive publishers selling tons of games. Arguably indie games that only sell a few copies need a larger cut than EA on their latest blockbuster.

There isn't much in the way of scale here. Their bandwidth isn't monitored on a per game basis, and if that was a factor in the cost they'd be basing the cut on the size of your game. Some 1 gb indie game pays the same cut or larger than a 100gb mammoth from EA. Valve is also way more strict with that indie game in getting itself published than they are with the EA game as well.