People are happy using Chromebooks as development platforms because they're $250 for an ARM laptop with long battery life, and you can hack them to run Ubuntu, not because Chrome OS has any merit on its own.
Things that are cute on a $250 machine are not so cute on a $1,300 machine...
I have two Chromebooks. One with 3G, that runs the stable ChromeOS, and the other wifi only, runs ChromiumOS, latest ToT, mostly because I'm working on getting ChromiumOS to run on our hardware, so it's a bit easy to compare and contrast when things are working and when they aren't. It's dead simple to boot off an sdcard or USB stick. The Chrome/Chromium did a REALLY good job at making the information available.
I'll probably buy the Pixel as well. The more I use ChromeOS, the more I realize how much time I waste on other crap that doesn't really help me get done what I want to do. And using ChromiumOS, there is the "dev_install" command which will set up a Gentoo chroot in /usr/local, that points to the machine that you built it on, and if you're running the devserver, you can run emerge pkgname, it will shoot it off to the server to build it, and once it's done compiling, installs in the chroot. There is also gmerge which will install ChromiumOS packages for you (e.g. A new version of the browser or maybe a newer kernel, without rebuilding everything) OR you can build a new image, hit up the Help page in settings and it will generate a diff on the server and update the entire install to the latest image. It's really an interesting setup, and I really like it.
Everything goes through gerrit, so you can even help out with version bumps and or patches fairly easily. The documentation is really good, and if you happen to hang out on IRC, the ChromiumOS developers are extremely helpful when something isn't clear, and even update the documentation for clarity.
I believe it's much easier to hack this one to run Linux than any ARM-based Chromebook. It certainly has enough memory, storage and processing power to be a decent development machine (provided you avoid heavy IDEs).
It's likely possible to even run Windows on this machine.
It's already braindead easy to put Linux on the ARM Samsung Chromebook. One of the first things I did was to assemble my own personal Linux distro and besides having to copy some blob files out of the original ChromeOS image, it's all very straight-forward stuff and I pulled up about a hundred packages I wanted including an X.org stack without fuss. The compile speeds are adequate if you aren't cross-compiling, I've certainly put up with worse.
I personally have little interest in the Pixel based on the specs. I think X86 is excessively 'big iron' now for a majority of needs and I find the lack of USB3 is mystifying. The screen looks interesting, but it's nothing I actually /need/ and certainly not worth another thousand bucks. I've personally taken to just using X86 for storage/cross-compile servers for the rest of my cheap ARM/MIPS/etc. crap and I've made it a point to stop buying expensive hardware. What $250 buys you now is actually pretty ridiculously awesome.
* Drop Crouton[2] onto Chromebook to get a full dev stack and unfortunate Ubuntu/XFCE environment.
* Set up chroot and start building other people's crap.
* Write to SD Card/internal storage and reboot.
Which step here is hard? Tedious to roll your own I'd give you, but you don't even need to as there's stuff like ArchLinuxARM[3] which skips the middle two steps.
Not gonna lie, I just spent several minutes trying to figure out what context sensitive notifications for Android had to do with hacking the chromebook.
Things that are cute on a $250 machine are not so cute on a $1,300 machine...