I admire Firefox for what it's accomplished, but Chrome has stolen my heart. I had to use Firefox today actually to test something, and discovered a Bing bar that I'm pretty sure I didn't consent to, taking up valuable real-estate.
Why does Firefox allow this?
We can't prevent this from happening so we try to provide a good way for other software to do it, so they don't do it in terrible ways:
http://code.google.com/chrome/extensions/external_extensions...
This is a historical accident; only toy and mobile OSes have any sort of application-level access control.
Wrong, they can just add DRM.