Microsoft is, and always has been, about collecting as much money as possible, while doing as little as possible. "Stealing" MS-DOS and making huge profits from it, repackaging an OS as a "new" version with very little differences... we've all heard that before.

So why should the keyboard be any different? They could potentially ingest massive profits because unlicensed keyboards (aka "not Microsoft") use the buttons associated with their patent, depending on how the courts interpret the depth and reach of this.

Also, this might be a play at what I've thought they might do for awhile: try and control and own as much of the computer as possible. As people move to Macs and Linux, it's probably becoming more and more attractive for them to disrupt competitors by simply "owning" the technology. If your keyboard (or any other common component) ends up being radically different on a Mac (besides the minimal differences now), users might reconsider switching.

Next they'll concoct a strategy about LCD monitors!