I'm saying that--by your logic--
any changes made to the franchise are not "legitimate," because Kamiya hasn't been involved. Character design, story, action... So you are in essence making a deal about
any changes whatsoever.
Obviously DMC and the genre in general owes a lot to Kamiya (and Mikami), but it seems rather rude to the rest of the team to say "nope, no changes, guys. No deviations. No personal touches. No experimentation. Can't do it!"
DMC2 was a stumble, but nowhere near a "came close to destroying" considering how many copies it sold. One could of course thank Kamiya and the strength of the first title (and that a drop would be expected if your creative direction went elsewhere), but then DMC3 was a solid return to form with a lot of expansion, and even DMC2 brought in a number of elements that stuck with the series from then on. And DMC4 was a strong-enough entry, even if it didn't continue a DMC3 legacy of improvements.
While DMC was all manner of influential, I don't believe Kamiya gets to claim anything introduced in the next
seven years be default. Enhanced sales can be attributed to appreciation of the series and its legacy, but it's not like if DMC3 didn't revolve around Dante it would have been a bad game. (And heck, even DMC2's camera issues probably would have been forgiven if it had higher difficulty modes.)
Meanwhile, nothing
is clear about the new DmC title from the Ninja Theory perspective, except that they were apparently trying to hang fairly tight to the original image first, and Capcom kept pushing them further away. So now they have a different look and a story that's been signed off on.
Might Capcom be making a mistake is pushing a reboot? Quite possibly. But hey, their series their prerogative. Might Ninja Theory be the wrong match for it? Possibly, but hey their title their prerogative. What will NT do with the opportunity...? We'll see.
Too many people are taking this as personal insult, however. The original title was not awesome because Dante was the character of all characters, his design the design to end all design, and the story was the story to end all stories... Frankly, both Dante and the story were pretty stock, but enjoyable. What set DMC apart was the gameplay. It broke the ice for what 3D action/hack-and-slash could do, and opened the door to your Ninja Gaidens and Gods of War, among others. It's also the only thing people really judged the other DMC's on, too.
I think from a story perspective, NT is likely to deliver much better than the other DMC's, to the point that one would "get the new Dante," or at least forget initial knee-jerk objections. From a gameplay standpoint, however...? As with any of these games, "we'll see."
The proof of the pudding is in the hugely-stylized combos.