There's a lot more to it than just "buy" them all. Apart from the fact that it would be absolutely stupid financially for microsoft to buy these studios as has been seen in the past the people who own and work at the said studios would see it as a "take the money and run" hence leading to yet another rapidly declining company (Rare), the laws would be looking into if it is fair and not monopolistic.
"...the best way to prepare [to be a programmer] is to write programs, and to study great programs that other people have written. In my case, I went to the garbage cans at the Computer Science Center and fished out listings of their operating system." - Bill Gates (Microsoft Corporation)
"Hey, Steve, just because you broke into Xerox's house before I did and took the TV doesn't mean I can't go in later and take the stereo." - Bill Gates (Microsoft Corporation)
Bill Gates had Mac prototypes to work from, and he was known to be obsessed with trying to make Windows as good as SAND (Steve's Amazing New Device), as a Microsoft exec named it. It was the Mac that Microsoft took for its blueprint on how to make a GUI.
""Windows [n.] - A thirty-two bit extension and GUI shell to a sixteen bit patch to an eight bit operating system originally coded for a four bit microprocessor and sold by a two-bit company that can't stand one bit of competition.""
