I totally agree with you, except for the "not leaving LinkedIn" part. I closed my account about 1 year ago after having to deal with spam, bad UI, and useless connections.

Also removing your profile from the network is a bad use experience: I had to send a customer support request to close it because I had more than 500 connections.

I think that I will build something in the near future because I like the idea of collecting connections and achievements concerning my professional career, but I'll never use LinkedIn again.