That is a good question and I am fully on your side. I have already voiced my negative opinion on the Kuvo registration in another thread that was closed promptly...
Regarding the playlists I think there is an option to not connect and share anything with Kuvo. I had a quick look at rb 3 a few days ago and I think I saw that thing.
Regarding privacy I also find annoying that I have to register again to another web service to have something that I already had before. Especially considering that in my case I have given quite a lot of money to Pioneer for my 2 cdjs, I'd find preferable to have rb already registered and available without having to register again.
I do not even know if rb 3 works if you are not connected to the internet or (hopefully) something is written to your computer when you register to kuvo. If somebody could shed some light on this, we'll be happy to know.
if you want to make sure that nothing is shared there are some ways that if discussed here obviously would lead to another swift closure of the thread >:)