Definitely geared toward toddlers, IMHO. I haven't read them all, but I would have found the "nice" one too vague. I never got what "being nice" meant as a kid (although I did develop some manners, or at least I often know what I
should do - or should have done, ack!). Finally decided "being nice" means "you do what I want", and as an adult, I still think that's about the size of it.

Now if they'd titled that one something about having manners, then it probably does what it's supposed to. But in terms of defining nice, no.
I doubt the "divorce" one would have done anything for me at age four, either. But maybe the ones on more concrete stuff, like riding the bus, would be helpful.
Toddlers? I'd probably struggle to follow them when I was five. I think the rest of my class would have been given such lessons. Year 1 and 2 may have been too old for it.
I don't think of it as dumbing down. We'd be given that kind of stuff in the early 90's.
The bus one was interesting because an autistic child might be confused when asked to walk all the way to the bus and listen to teachers. I'd probably not be able to do the two together.
edit: that read aloud one gave me flash backs. We were always told not to touch other kids and basically shut the hell up while the story was read.