Gamers can pre-order Battlefield 3 at Origin.com as well as over 100 digital retailers worldwide. EA offers games to all major download services. Unfortunately, Steam has adopted a set of restrictive terms of service which limit how developers interact with customers to deliver patches and other downloadable content. No other download service has adopted these practices.
We are intent on providing Battlefield 3 players with the best possible experience no matter where they purchase or play their game, and are happy to partner with any download service that does not restrict our ability to connect directly with our consumers. We hope to work out an agreement where Steam can carry Battlefield 3; meanwhile, gamers can pick from the more than 100 digital retailers listed at http://www.battlefield.com/digitaldownload, or go to http://www.origin.com.
As you said, the value in Diablo 3 lies in the multiplayer. I'm sure there are some people who only touched the SP but many people simply already played D2 the way that they're limiting D3 so they haven't really lost anything.