Let me avert your attention to Kingdom hearts...Call of Duty, Sports games, Dead Rising, Grand Theft Auto, God of War,Soul Calibur, Tekken...there are more games out there too...love them or hate them...they haven't changed anything...they added some stuff...but the main concept hasn't changed in none of the games....like the saying goes...if it ain't broke don't fix it...
Those things have gone through changes as well. The difference is that the changes weren't radical. For example, Soul Blade/Calibur/etc. always adds new stuff to their games. Random characters from other companies in SCII, an arcade rpg-like-story mode in SCIII, along with a strategy-like game story featuring your own character etc. Haven't played any of the PS3 SCs. I heard though that there is no normal guard in SCV. If that's true, here you go.
The same for tekken. At least up to 5, that I know about.
God of War also evolved, game after game.
As for the sports games, and games like Call of Duty, I can't really talk because I'm not a fan of either of them, so I'll take your word for it and accept that they don't change, except from adding more players, weapons, teams and that kind of stuff.
However, those games do not NEED to go through a radical change. Sport games that come out every year just need to have the teams and players that were popular that year. So all they're doing is following reality. They don't need a scenario writer. And I'm guessing we're not discussing changes in gameplay unless they're super different. After all, DmC -the main game of this conversation - wasn't "hated" because of the gameplay. But because of the radical changes in the protagonist, the story, and the world. Maybe the word "atmosphere" sums it up. Same thing happened with the games I mentioned before, SH & RE.
Change is upon us, but comes in many forms and appearances. It is the changes in the atmosphere and feeling, and characters that creates the hate. And this kind of thing can only happen in games that actually have story. Sports and Call of Duty do not require any advance story-telling. I'm not saying DMC in general has anything advanced, but I'm pretty sure they hire scenario writers for even that little story they create in their games.
Tekken & SC are fighting games. Not much change can happen there as well. Add new characters, new moves, a general background and a villain, a small video that each character beats the villain at the end, and here you go. No need to sit down and think about any real character development, apart from the one that happened in between games (that we never see). Example for that. Raphael was kind of a bastard in SCII, but not quite mad. In SCIII he became a psycho. How and why? Who knows? They are probably blaming everything on Soul Edge or something. See my point? And in Tekken, they always go through all the trouble of creating a tournament to sort out their differences? Why? Because. Not real storytelling needed cause we both know most buy the game to play with their friends. And that's ok. But changes do happen, just not the kind of changes we see in action/rpg/adventure games.
So my whole point is summed up into this:
As long as there are radical changes in the game's atmosphere, the main character and the whole feeling, THEN the fans are sure to rage. They hated Nero because he wasn't Dante. They hated Raiden because he wasn't Snake. And the list goes on.
Hope we sorted out this.