Developer mode's designed[0] to avoid using it to bypass CrOS's security. The relevant points:
* the 5-minute wipe both hinders access to the owner's data and makes it unlikely the OS can be replaced with a malicious variant without being caught in the act
* the warning screens ensure the owner's aware they're in devmode
* Hiding the Ctrl-D bypass makes it appear the only option is recovery, you won't know about it unless you've enabled devmode yourself.
* the 5-minute wipe both hinders access to the owner's data and makes it unlikely the OS can be replaced with a malicious variant without being caught in the act
* the warning screens ensure the owner's aware they're in devmode
* Hiding the Ctrl-D bypass makes it appear the only option is recovery, you won't know about it unless you've enabled devmode yourself.
[0] http://dev.chromium.org/chromium-os/chromiumos-design-docs/d...