It's like you've never actually experienced the autoupdater and are only responding to a rough description of the process. It's a HUGE win.

  > What if it sucks down bandwidth when I'm on 3G? 

That might happen. What if it does?

  > What if an update breaks something, and I'm in the middle 
  > of something that can't be updated? 

As per TFA (and experience): The autoupdater never interrupts you. The only UI change is one of the toolbar buttons changes subtly. Most of the time you don't notice that an update is ready to install. More to the point, after the update you usually don't even notice anything different.

  > What if an update silently breaks the update process? 

There's absolutely no precedent for this, but honestly, who cares? This is hardly reason to shun the entire system.

Bottom line: The autoupdater makes sure I never care about the version of Chrome I'm running, just like a web app.