"Shouldn't we DMC fans be grateful about DmC instead of acting like it was something unwanted?"
Um no not really. I wanted the DMC story to continue and fill in all the missing questions, not begin with something other than whatever NT's version is supposed to be. If they
completed the series then decided to go with this new version, then it probably wouldn't be so bad across the board. Hell, even a few well-developed animes answering the who, what, when, where, why and hows' of the series would have sufficed plenty, and then on with DmC they could go...if they will
(kinda see Capcom going down the bankrupt gutter sometime in the future)
And like my signature says "Do not fault people for not having an interest in something if it
does not feature the things they care about." This doesn't only apply to games it's all over the media spectrum.
For example, Chris Cornell, who is known for being the lead singer/rock singer in rock bands like Soundgarden and Audioslave made songs such as these:
When he decided to go Hip-Hip and R&B, his fans of the rock genre damn near
castrated him; calling him all kinds of 'sell-outs' 'phony' and voiced their overall betrayal. Granted he can do what he wants, but the majority of his audience/consumers turned their backs on him. Since then Chris has gone back to his "roots" so to speak.
When you have something that people like, no matter how big or small the fanbase, then decided to switch it up to bring new people in/bring in more money, while leaving the initial group pf people in the dust, you're going to get a lot of unhappy people having a product changed that they aren't "grateful" for. I personally do not care for the techno/dubstep music and the whole pop-punk, retro R&B feel (amongst other things) that was implemented into a gothic-esque, rock-opera game, so I wasn't happy with the product (maybe if it had a darker edge to it then okay but that's a story for another time). I understand that people want to try new ideas and bring change to certain things, but others simply want new ideas to "fit" into the established product and others want things to stay the same. You could argue that a series will become stale if they use the old same-old, same old, but then look at (eyeroll) the COD series.
It kinda really boils down to preferences.