As @DrAzzy says - while the CC3000 supports WEP, Espruino just sets it up for WPA2.
It wouldn't be too difficult to add the option, but so far you're the only person to ask for it :)
@Gordon started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
As @DrAzzy says - while the CC3000 supports WEP, Espruino just sets it up for WPA2.
It wouldn't be too difficult to add the option, but so far you're the only person to ask for it :)