Never afraid to speak his mind, GNU founder and PC-rights campaigner Richard Stallman has called Valve's decision to sell DRM-laden games on Linux "unethical." Steam recently announced that it would port its client and popular titles to Ubuntu 12.04 LTS, with Left 4 Dead 2 for Linux well underway – a move that has been positively received by many in the Linux community, which has been largely ignored by major commercial software developers.
Although some folks see this as a turning point towards making Linux more popular, Stallman believes closed source games are "unethical because they deny freedom to its users." He added, "any GNU/Linux distro that comes with software to offer these games will teach users that the point is not freedom. Nonfree software in GNU/Linux distros already works against the goal of freedom. Adding these games to a distro would augment that effect."
However, Stallman does concede that efforts by the likes of Valve could possibly boost adoption rates of Linux. "It might encourage GNU/Linux users to install these games, and it might encourage users of the games to replace Windows with GNU/Linux. My guess is that the direct good effect will be bigger than the direct harm."
It's important however to note that the problem isn't necessarily the cost. Even if Valve provided free games to those on Linux, it's unlikely the game developer would release the full source code for everything, so it works against the "freedom" of Linux in Stallman's eyes.