OP, I know exactly what you mean about the classes "being magical".
My DGD is nearly one, I've been to a few and had to supervise classes as part of my job. I wish that they had been around when mine were little.
My DD had my GDG at 19, she felt and was judged, people were very rude until they found out that she had a Home Birth and BF.
I went with her because she needed the routine, she had anxiety.
There were a range of Mums getting to grips with the change a first baby brings.
"" My DD's main problem seems to be that her father wouldn't join in, he'd just watch from the back. I don't see why this would be an issue personally ""
I think you forget, or perhaps you didn't, the range of emotions, including insecurity that new Mums can feel and a class of any type should be tailored to suit those it's supposed to serve.
I'm very involved, my DGD had health problems, but I've encouraged my DD to keep her routine up, but I don't go to the classes, because she needs to interact with the peer group, uninterrupted and be able to have a conversation with other Mums.
If there were relatives (especially an elderly man) sitting on the side lines, I know a few Mums wouldn't go and these are the ones who are the targeted demographic.
The reason I say "elderly man", is because the Women want to share their experiences of BF and restarting their Sex life etc.