Just remember, Steam doesn't necessarily set the prices for games on the site -- they've asked publishers about the prices they'd like to sell games at. Publishers have to approve the pricing, or they have an option of changing it. With The Witcher: Enhanced Edition we asked them to lower the price in Europe (well, Eastern Europe, where the game is available on Steam) to be in-line with market expectations.

Valve sent us an email basically saying "here's what we're doing and here are the prices we're planning to use -- let us know if you need them adjusted" and I'd suspect that other publishers must have gotten that same email.. particularly considering the fact that we only have one game on Steam, so we're a minor player.