StingingVelvet: Refusing to sell Steamworks titles is like pretending Steam does not exist, which is silly. Exposing your customers to Steam is a non-issue at this point because Steam is so well know and required for so many games.
What I did like and wish still happened though is Steamworks games going up for sale elsewhere with the Steam requirement removed.
DelusionsBeta: Ultimately, it means increased competition for game sales. I've seen no evidence that Valve gets a penny for every copy of Magika bought through Impulse, Gamersgate and Direct2drive, yet I'd imagine the fact that they all selling the same game would prompt a firm increase in price competition between the distributors (see also D2D's regular 15%-20% off codes).
the big problem with steam is that it's client is first and foremost a marketing tool for for Valve's storefront. 99% of what steam actually does could be done without without constantly pushing it's users into browsing Steams catalog, hell most of it could be done without a visible client at all.
think from a normal retail perspective, how comfortable would you be selling a product that required the customer to walk into a compositor's store in order to use it?
just to make this example simple, I'll stick to video games: if the only place you could get 360 games was from Walmart, how comfortable do you think best buy would be with selling Xbox 360's?
sure, best buy would get a little bit of money for the console sale, but by selling that console they have just
guaranteed the customer is going to go give money to a rival. not just money for the games, but also for most every other incidental sale on an item that they could have gotten from Best Buy, but since they are already at walmart ....
I despise having Steam's shitty little client rubber necking over my shoulder, but the real reason I don't buy from them is because of how much they are trying to downward spiral everyone into exclusively playing PC games on steam.
(aka monopolize the market)