I also think it'll kill adoption of Ubuntu. It made me adopt a different distribution, and I think it will cause others to do the same.
The distinction between the desktop and the Internet is going away. Some argue that "the desktop is dead"; I just think that it'll get more integrated.
I don't think that this is necessarily a bad thing, providing that you have adequate control over your own privacy settings and have a choice of providers (both large and small). An open source project that is promised to always remain so is the safest place for this, since you'll always be able to find instructions to turn things off if the defaults don't suit you.
I much prefer this over the world switching to web-based hosted solutions for everything.
I fixed it with: sudo apt-get remove unity-scope-musicstores unity-lens-video unity-lens-music
(I couldn't find how to disable it)
It's not like I agreed to this when I installed the system, because I upgraded from a previous version (and a previous version, etc), and that behaviour wasn't there.
I don't know how Canonical could advertise these changes, but in the Amazon lens case I think RMS did it right.
EDIT: at least I couldn't find a way to disable them. Nothing in privacy settings and nothing with dconf-editor.
But if more among us adopted this nuance, it will kill most arguments before they are raised. :-)
Well put.