One danger of any instructional system is that the student will only retain the material as it pertains to the classroom context. Last night a teacher told me that their "social-awareness" curriculum seemed to work great, until they watched the kids on the playground. In class, the kids applied the negotiation and mediation skills, but not outside the classroom.
I've had math teachers tell me they couldn't think of a real-world problem that could be solved with the math they were teaching.
With educational games - on a computer or not - social or not - the fear is that the students will learn the rules of the game, which are loose abstractions of physical reality, rather than the rules of reality. Oregon Trail taught everyone that each settler needed 99 bullets, and that you could be killed by some wild animal called a "dysentery."