Comment As someone who has released a game on Steam... (Score 5, Interesting) 32
They took care of content distribution. They took care of international sales / taxes / etc. They took care of currency conversions. They took care of folks who wanted returns (not many, but still).
They made my game accessible world-wide with almost zero effort on my part.
Did I give them a 30% commission to sell my game? Yes. Would I like that percentage to be lower? Sure. Would I call it excessive? Hell no. Especially since retail stores get a similar cut, and I didn't have to worry about manufacturing, distribution, stock, returns, etc.
~D