As I've said before, it seems to me that the new staffers in charge are taking a really corporate approach to how they handle the show now, and that's really a shame, because SST was never a corporate show to begin with, nor was CTW/SW ever really a media conglomerate. I'm still convinced that Sonia's departure wasn't entirely of her own volition - I know she said it was, but it feels like there was more going on behind the scenes that anyone's letting on: as soon as she left, they immediately brought in a much younger Latina as a character replacement for Maria . . . that right there is a very common corporate practice in show business, and it has been for the longest time: even Billy & Mandy poked fun at that with the Elvira expy Grim loved watching, saying the network was letting her go now that she turned 30.
Now, I suppose in a sense that kids today would probably be able to relate and respond better to younger human characters like Chris and Nina, but the older humans aren't just characters - in a sense, they've also been like parental figures, not only for the kids watching, but for the Muppets as well (hence one of the reasons I found it strange Big Bird was singing about how Nina's been like a mother to him, even though prior to that, they only interacted with each other once); I suppose with the younger humans, it would be something more of an older sibling kind of dynamic.
Personally, I'm not entirely upset we're losing the older cast members: I mean, let's face it, we all know they're not going to be around forever anyway. It's just the way they're being cut loose like this that leaves a bad taste in my mouth.