Yea, for sure, normal people wont setup a Chromebook to dual boot. I only keep ChromeOS on it for others to use but everyone that I have let use it has found it to work great. Several of them have ditched their larger and heavier laptops to go with a c720 and they are all quite happy with them as all they really need is good battery life and access to a browser and email.
If I remember correctly the 64GB SSD was only about $25-$30 so the total cost of the setup was right around $200. It runs Ubuntu 14.04 very well as long as you don't need to run anything that requires over 2GB of RAM. I get 6 to 7 hours of runtime on it and since I mostly need it to access web interfaces or run SSH sessions (or serial via minicom) it fits my needs very well. Its probably not an ideal setup for everyone but for average folks ChromeOS gives them what they need and if you need a bit more loading your Linux distro of choice is quite easy as long as you put a larger SSD in.
As with everything in life you need the right tool for the right job and I find this cheap tool to be a really handy one to have in my arsenal. If I need to do some heavy lifting I will take a fully loaded MacBook Pro with me but most of the time I just don't need it so it stays in my trunk. For really serious work I have a small 1U (not very deep) with two quad core Xeon's and 16GB of RAM that I will just toss on the LAN and use the c720 to SSH to it...works way better than using the MacBook and only weights slightly more ;)