Well, they're not the only fans.
Personally, I think most people on message boards are
far too conservative, doesn't matter which series. If NeoGAF could develop games it would be the same, over and over again, doesn't even matter which game.
I also understand that playing around with franchises leads to frustration because you obviously can't satisfy everyone.
Look at the Zelda series, they tried so much stuff with the series (art style, gameplay, etc.) that it's horrible to argue with fans which one is the best or how the series should look like.
Personally, I don't care about this stuff anymore, I play the game and if it's good, it's good. Developers are creative people and they want to try new stuff as well.
Only listening to the "Don't change my game"-fans is not the way to go, doesn't matter how much they complain.
But I also understand and
appreciate the conservative people, because I also like the tradiotional stuff, but wouldn't complain as much as they would.