Activision targets the console market, while Rovio's main target is mobile devices. There's a lot of overlap between the two and the line between them gets blurrier every day, but for the time being they're still two distinct markets.
The market isn't the point.
Rovio is still milking Angry Birds as much as Activision is milking Call of Duty but there's not a single peep from one of you. Many of you are targeting Activision just because it's the "in" thing to do, but couldn't give two craps that many, many other companies have been milking many, many other franchises for decades. How often do non-Final Fantasy named titles get passed out of SquarEnix's door, or when it was just Squaresoft? How many Pokemon games are there? Mario? Zelda? Tetrist gets remade by seemingly everyone and none of you bat an eyelash. So why is Activision the witch being put on the stake?
Let's take Capcom, on just the 360 and see what we come up with:
Three Dead Rising games
Two Devil May Cry games
Three Lost Planet games
Three MotoGP games
Four Resident Evil games
Four Street Fighter games
Two Marvel vs Capcom games
They had five,
five other single none established IP games. 26 total games in 2012 and 21 of them were either new IPs that got sequels or established IPs with new sequels.