If people are content to read stories that adhere to a particular status quo, then it shouldn't be changed on a whim. If the series has stagnated so that no one wants to read stories that adhere to it any longer, then changing the status quo is warranted.
The problem there is that both sentences assume the entire audience will want the same thing. That's never the case. Any decision that delights part of your audience will upset another part. Which is why you ultimately have to go with whatever feels right to you as a storyteller and not be guided solely by what you imagine the audience wants. If you believe in and care about what you're writing, and put your best effort and passion into it, that's probably the most reliable way to satisfy the most readers. In that case, even people who aren't crazy about your story decisions might still find something worthwhile or meaningful in how you tell the story.