Probably? Probably what? Probably that they're a bunch of good people? Probably that this was the game that they wanted to make? Probably that this is their franchise to do with what they want and it's their game?
There are many different Halo fans, and from that many people have different opinions of what can work in a Halo game and what can't. The majority of these changes, to me, says that 343 is trying to keep the Halo experience fresh while at the same time trying to provide that same core experience. I wouldn't want a new version of Halo 2 to be released every three years, and I'd be hard pressed to find new ways of keeping the experience fresh while trying to keep the same core experience. With these changes you lose some fans, like me, who simply disagree with the direction.
As for campaign, the best I can do is write up a large critique and hope that 343 takes some of those criticisms to heart. What's good about my criticisms is that, were 343 to address them, they won't detract – indeed, they should only add – from the enjoyment of people who like what 343 has done with Halo campaigns. If not then I guess I'll just move on. As I said: What are you gonna do?