Beyond goodwill – which imho would likely be relatively minor given what the average gamer cares about – open-sourcing in the hopes of stimulating mod support is a very cool idea. It looks like EA is providing a map editor, but having the DLLs out there makes it more possible for dedicated users to really tinker with game logic and internals, and (hopefully) create the kind of ongoing sophisticated DLC for other players that EA isn't willing to create and sell itself.

I wonder if active support for open source by game companies will eventually reap the benefits it ostensibly does for big tech companies. For example, by open sourcing React, FB not only can influence JS frameworks in general, it can cultivate a hiring pool of engineers already familiar or proficient with React internals. There's already limited precedent with game companies hiring creators of big-time mods (Valve hiring the creator of Dota). But I'd think more open source support and reducing the friction for fans to become creators would surface even more talent.