To clarify: If all smartphones were basically just an encyclopedia, instant messenging and music device I think they would be much better for people. Currently, most time on a smartphone is spent engaging with the attention economy, which I think is where most of the real poison lies.

I think even if you got rid of the attention economy though, smartphones would still have negative consequences. A smartphone will help you kill some time, even if you're just browsing wikipedia. I think sometimes it's good to be bored, it can spur you into doing something new. Now we don't get bored, we get placated.