You can't build for NaCl from CrOS, and as it stands you don't have the toolchain (editors, debuggers, shells, etc) one's used to on other platforms. I understand a $400 phone not being able to run it's own toolchain, a $1300 computer less so.
Hell, just adding some project management to the inspector to act as a psuedo-IDE for Chrome apps would be a start. I've got personal attachment to *nix from using so much of it, some 12-year old that stumbled into the devtools has no such attachment.
Besides, the fact that Chromebooks are running linux under the hood is an implementation detail. They could very well be running FreeDOS as far as the user should be concerned; the platform is Chrome.