If you need to be told why Activision is a shit-stain on gaming's underpants, you need only look at the competition.
Take Valve. Valve were onto a winner with Half Life. Did they cash in on it? No! Instead, they patiently built a truly EPIC sequel, one so grand in scope it technically isn't finished yet, despite having been released in three parts. As much as we would all like Half Life 2: Episode 3 (Manchester City nil) to come out tomorrow, I suspect we would all be very disappointed if every six months Valve released another "episode", charged as if it were a full game yet delivering 1/4 of a full game's new content.
Ubisoft and Assassin's Creed are next in line for my example. AC1 was full of promise, but didn't really deliver. AC2 was a wonderful improvement. Brotherhood was just all about polishing the mechanics to a mirror sheen. Activision would have stopped there, but Ubisoft clearly felt that charging £50 for a graphics tweak and one new map to the loss of half a dozen old ones wasn't very fair... so they went and bolted on one of the best Multiplayer experiences I have ever seen. Then they give us not one, but TWO free "patches" with new maps and game modes, and their third expansion blew the roof of the whole affair by somehow making the multiplayer even more of a paranoia factory!
Honestly, what do we all think of when you hear Activision? We think "yet more Call of fucking Duty and Guitar fucking Hero." We're sick to the back teeth of them selling us the same game over and over, but just to add insult to injury we then add the plethora of news stories, which someone is bound to have linked by now, that prove Activision really doesn't give a crap (trying to stop Brutal Legend is my favourite example of Trolldivision's business model).
Remind me; why is this hate unjustifed again?