There's also the imaginative aspect. These theories can become sources of artistic inspiration once cleaved from the world of facts. Something like Burroughs' concept of language as virus is just a really convincing way of thinking about language too. I don't know how well it holds up under academic scrutiny, but it makes sense to me and seems like a helpful way of picturing the thing as a whole.Those recapitulation theories are brilliant. Darwins theory of evolution by natural selection is what won out, but there were loads of variations for a good span of time.
All the also rans are important so you understand there were other options. Things could've turned other ways.