Someone recently asked me if I taught "nunchucks" as part of the FMA program at Martial Arts Koncepts. My response was that traditionally it fit within both the FMA (the Tabak Toyok) and JKD programs as an impact weapon and is taught, but not very often. The reason being that you're going to be hard pressed to find a set of 'chucks lying around to use in the event you need them and if you carry them as a defensive weapon it could mean a felony charge for you and at least a night or two in jail. While I always enjoy training with them and teaching others to use them, I don't make being functional with them a requirement for my students.
BTW - the following video is a perfect example why I don't teach 'chucks often. This is not a baseline for martial skill it's more like baton twirling.