They are two separate points.
MS gets a presence in Asia which is significant since it has none and has still sold more than the PS3, and at the same time denies Apple(OS/Tablet/phone) any future Blizzard games.
Exclusive sell consoles, what isn't big now doesn't mean it won't be latter. COD wasn't big to MW. As for controllers vs mice, DS3 worked pretty well with a pad, I doubt D3 and on couldn't do the same. Then you have Starcraft which would works as an FPS/TPS/RPG. IMO if MS were going to put up for Activision, they would go all out and acquire Blizzard too.