There's a lot of legal reasons why MS won't buy EA. For example, Madden is required by the NFL to be on every system, or they lose NFL exclusivity.
Never mind the fact that EA makes money by being multi-platform, so if MS bought them they would lose most of their value because they would pretty much lose money on everything. Same reasons people argued that Sony wouldn't buy Take-Two back when rumors on that came up last year. (Notice how instead it's EA, another third-party, who's trying to buy Take-Two.)







