If new designers take over a work they are prone to bad work. New ideas in a game is good but you must have a clear vision of what makes a game great.
Let's take DMC for example. After DMC 1 Dante and the story went down the drain. And it seems it's because Hideki left Capcom because in Bayonetta you see alot of DMC stuff.
Someone said "Eva" the mother of Dante may have been a witch (which is a good theory), and guess what Bayonetta is about? Witches.
And new designers often tend to do what they want with a established character. They will make a story "HE or she became like this because X" just like you said.
I have a foundation for a character of mine. And i am working on ideas for him.
But let's say if i make the game i want with main character that i have thought out. But then i don't get to make the sequel because i leave the company or something like that.
Then the ideas that i have had ready for the sequel would go down the drain.
I didn't like Bayonetta at all, so... :/ I don't feel like that's a great loss. Having the same director on board doesn't really guarantee success. Look at Castlevania. They had Iga all the way, but the series still stagnated.
DMC... well, I feel like you can clearly trace the path of what went wrong. I remember hearing a theory how DMC2 was originally meant to be an entirely different game, about Lucia, which got cannibalized into a DMC game. They understood that DMC1's story was over and tried to start a new chapter, but the effort was totally half-assed on all fronts (story, gameplay, you name it).
Seeing the failure, they tried to go back to the roots, but they went too far in using only existing ideas. So we got a prequel, with a first novel's notion of Vergil, the second novel's style of heroine, and a younger Dante with his "coolness" exaggerated.
But Dante's story was basically over after this. So what to do? A traditional passing of the torch story. So they made a new character who was like Dante, but not. (I like Nero, really. But there's no point in denying this. Actually, I think Nero acts quite a bit like 1Dante...) Meanwhile, they kept the exaggerated Dante of 3, but made him older. The problem was, they didn't really set up or explain anything that happened, so fans were left with a whole lot of confusion.
DMC isn't a long series, so it feels like it never really found it's stride to start with. We have the Original, a failure, a prequel, and just one actual sequel that is filled with weird plotholes.
