Patents have bad reputation with the tech community, which means that if now MS presses hard Linux and other products it will have trouble hiring good devs later. But if they just support and milk their existing products they don't need good devs so much.
That would be a very good option for the ppl holding MS shares, but can do insane amount of damage to the IT industry - monetizing all those patents without fear of losing reputation among developers, students, etc. and without having to worry about new products being affected by other people patents. Team up with the super-corrupted music/movie/TV industry to make non-DRM devices and OSes illegal by bribing politicians.