Many times in the past and of course now recently, we saw many Videogame series get alienate for many different reasons.
Some developers say they wanted to try to make the series more darker and more serious that the previous games [Bomberman Zero], some others said they wanted to tell a different story than the original had [Devil May Cry 2012], some others wanted to change the gameplay entirely and make it a different style of game [Xcom 2012, the FPS], etc, etc...
When something like that happen, many people start rage to the developers for not trying to make the make like the original.
They rage for the new look of the main character, they rage for complete change of the gameplay, they rage for some tiny details that maked the game unique and the list go on...
With that said.....
Why we don't see this kind of rage in some other Videogames that they as well changed a lot from the original games?
Why for example they didn't raged about the Doom 3? Doom 3 is a very good example of alienation of the original game. Doom 3 have a different look, the monsters doesn't exacly the same, diffeent type of action, the horror elements etc, etc...
But yet, the fan of the series [like me] didn't make it something so serious that believed it will "murder" the series.
Another example is Resident Evil 4. Seriously, the developers make the biggest alienation and stick with it in the others titles cause it had success. They made the Resident Evil series from a pure horror series, to a Fast-Third Person-Action B-movie series.
But again, never I saw a serious negative reaction for this game.
Of course there are many, MANY examples I can say [The Anime like Lost Planet, Metal Gear Solid Card game, etc...], but why we see this rage in specific games and not in some other game even they clearly changes a lot of things?