That's right. To some degree it makes sense -- most families probably don't want to share every photo they take. But most probably also won't bother to manually add every photo they do want to share to a shared stream. I'm not sure there's a great solution to this, but it'd be awesome if somebody figured it out.

My wife and I have a similar problem with our music libraries. I have all of our music in my library and on iTunes match. I'd like for her to be able to access music in iTunes match too, but there's no way to do that without sharing an iCloud account and thus sharing everything else iTunes related.