Color Sensor not allowed in FLL
For any FLL teams using the NXT 2.0 kit, note that the color sensor is not allowed in the FLL competition. The FLL rules allows for up to 2 "Light Sensors", and this refers to only the original NXT light sensor or the older RCX light sensor. The Color Sensor is not allowed, even if you only use it in "Light Sensor" mode. I verified this with FLL to be sure, and they confirmed. So if you have the NXT 2.0 kit, you can buy the original NXT light sensors separately from LEGO Retail or from LEGO Education.
I'll call this one a fair ruling by FIRST.
FIRST was very quick to pick up the NXT for usage with FLL, so I don't think it's an issue of "slow to implement" - with the Color Sensor, it's definitely got everything to do with availability. Unless (Until) LEGO decides to offer it as an item available for individual purchase, FIRST will have to block it from competition to keep things fair - the Light Sensor is perfectly suitable (still) for line-following and identifying the basic colors used on an FLL mat.
I agree, however, that FIRST should pursue trying to get the sensor more available so its features can be used in future FLL competitions.