Linux boots in 6 seconds. Caps is mapped to Mod4/super, you already have a GIANT control key. Linux does not need NM or Pulse either. And the operating system is not in the middle of being axed by Google, so while updates are not automatic I don't have to worry about them stopping.
But the two biggest points: Linux gets you an extra five hours of battery life, and lets you configure charge limits so that the non-replacable battery won't rot away in three years.
I can't remember when I last had a Thinkpad where any of that didn't work out of the box with Linux.
But on every single other laptop I have ever used Linux on, there has always been something that hasn't worked properly, whether it's audio not waking up properly after a suspend, or occasionally suspend not actually working and I discover a red hot laptop in my bag spinning at 100% CPU, or some such issue.
Having a machine which I don't have to fiddle with to make work is a totally new experience for me.
And then if I want to use a real OS, I switch to my fullscreen Debian installation running awesome and all my xterms and it all just seamlessly interoperates. Except I don't need NetworkManager or PulseAudio or any of that nonsense because ChromeOS does it all for me. The brightness buttons work! The audio volume buttons work! Suspend and resume works! Everything works! There's even two-way clipboard support! Which works!
I've been using Linux for years, and I think this is the first time I have ever had a Linux-based laptop where all this stuff wasn't a total PITA.