Anyone who's flown RC aircraft in the past decade knows all too well about this..

Spectacular light show, a good burn... yeah. Thats about it though... It wouldn't be worth a terrorists time... it would just be a light show and a smoke show, could start a fire, which would be bad, but honestly fires get suppressed pretty quick on modern airliners as long as they aren't started in the cargo area and ember for a while... in the end, any attack carried out with a LiPo/LiIon would just be an inconvenience...